(CNN) -- In the U.S., a referee is punched and later dies. Meanwhile In Europe, a Dutch volunteer linesman is beaten to death, a teenage Spanish referee is violently assaulted, and in Germany a match official is hospitalized.
They are almost as essential to the functioning of the game as the ball they bring onto the pitch for kickoff, but soccer referees across the world are feeling under siege.
Subjected to vulgar insults, threatened, chased off the field, attacked, hospitalized and, tragically, killed.
In the most recent incident, 46-year old Ricardo Portillo -- refereeing an amateur game in the Salt Lake City suburb of Taylorsville -- was punched on April 27 after booking a player. He died from his injuries on Saturday.
What is behind this apparent wave of violence, which largely affects those grassroots officials whose role is so vital in maintaining the development of the so-called "Beautiful Game?"
Some say it's the direct result of bad examples set by the elite echelons of the sport, some say it's a cultural problem -- and others point to the very parents who go to watch their kids play.
"You feel completely helpless," says Jose Giner, who looked on in horror from the stands the day his son was brutally attacked during a Spanish regional match in February.
Hector Giner, just 17, was savagely attacked in Burjassot, Valencia after attempting to send off a player who had insulted him.
As the teen looked down and began to write in his notebook, the player -- a policeman 10 years his senior, named as "Alberto M.M." in media reports -- struck Giner a blow in the face, then delivered two kicks to the body as he lay prone on the floor.
In hospital the young student lost his spleen and three liters of blood. His attacker has been suspended from his job ahead of the trial, for which the date has yet to be set.
A complex issue
That Sunday -- February 17, 2013 -- was an ugly warning for Spanish football, but it was far from an isolated case of arbitrary violence against the country's 15,000 referees.
"All parents will understand how I felt that day," Jose Giner told CNN. "I think referees in the lower leagues are definitely not as well protected as they should be. Those responsible should sit down together to take action."
The Spanish Football Federation (RFEF) acknowledges the need for solutions and says it has begun working together with the Spanish police -- the Guardia Civil -- to "initiate a protocol of security and prevention."
"Effectively, with the referees in lower categories we attempt to protect them in the best manner possible," Juan Castillo Jimenez of the Technical Committee for Referees at RFEF told CNN.
But the task at hand is a complex one, beginning with incessant verbal abuse from players and spectators which can be difficult to stop.
"Well, yes, there is a lot of verbal violence," admits Alejandro Urrego, a player in the same Valencia regional league where the Giner incident took place. "Referees are scared to show red cards to those insulting them for the possibly violent consequences."
The RFEF acknowledges that parents have become some of the worst culprits in aggressive behavior towards referees in Spain.
"Parents are worse than the kids," says Emilio Jose Ayuso, a 21-year-old referee who talked to CNN at halftime of a youth match he was officiating in Aranjuez, a small town one hour south of Madrid.
"There are a lot of insults from the sidelines. You just have to ignore it. There is nothing you can do about it."
Problem starts at home?
One Europe-wide manner of tackling the problem has been to move spectators further away from the touchline, thereby reducing their influence on referees.
Still, insults have become so commonplace that some refs have begun to take an aggressive attitude onto the pitch themselves, according to one parent.
"Parents are definitely to blame," says Cristina, a mother of two who watches her son play in the same match where Ayuso is the referee. She preferred not to give her surname.
"Two members of my close family are referees, so I know what kind of insults they have to hear, and ignore, every weekend.
"But I've also seen a referee who insulted the kids -- I couldn't believe my eyes when it happened in my son's game the other week. It also happens."
Another factor in Spain is that referees have traditionally been the target of abuse by football fans -- though usually verbal not physical.
"We blame everything on the ref," says Jose, a taxi driver in Madrid, who also did not want to give his full name.
"Even 'la crisis' (the financial crisis), if we could. The stadium is the place for Spaniards to vent their frustration. If parents set such a bad example, imagine how the next generation is growing up."
Bad role models
That lack of respect for match officials filters down from the top teams and players, according to journalist Cayetano Ros.
Last May, Granada forward Dani Benitez was suspended for throwing a water bottle at the face of referee Clos Gomez while his teammates contested the award of a penalty to opponent Real Madrid. The previous month linesman Cesar David Escribano was struck by an object thrown from the stands during a second division match at Cartagonova.
"I think we are all to blame, also the media," said Cayetano Ros, who covered the Giner attack for El Pais newspaper. "It is getting better than it was 20 or 30 years ago, but there is still a culture of pressuring the referees: it is definitely a danger."
At a La Liga match between Getafe and Deportivo La Coruna in early 2013, the referee sent off a home player early on, and was hounded by home fans for the rest of the game. Small children sat nearby listening to the verbal abuse.
Veteran Spanish football observer Phil Ball says it is a cultural model that needs changing.
"If you don't pressure the ref here, you're seen as stupid," says Ball, the author of "Morbo: The story of Spanish football." He calls it a "tactical" approach, and freely admits to talking to the linesman during matches his son plays.
"There's a saying in Spain: 'El que no llora, no mama' (he who doesn't cry, doesn't get the milk), and it's applied to football in Spain," Ball told CNN.
"I saw a particularly bad example in the Donosti Cup 2011 (a youth tournament), when a referee was chased off the pitch by a team called Ciudad Jardin from Valencia. You can't solve things unless you change the culture. You have to come down hard on perpetrators."
Ayuso believes that punishments are not enough -- education is the key.
"To become a referee, the Madrid Football Federation makes us take a course as well as two classes with a psychologist, because it is common knowledge that you'll be verbally abused," he said.
"I think a solution could be to give psychological classes to teams. That way they see that we too can make mistakes. But as it is, you definitely go to some grounds with a great deal of respect. Valencia and Holland are always at the back of your mind."
The problem of violence against referees came to worldwide prominence in December 2012 after a shocking incident in the Netherlands.
A group of teenage players beat 41-year-old Richard Nieuwenhuizen to death after a youth match in which he had been a volunteer linesman. His son had been playing in the opposing team to that of his attackers.
It was a tragic attack that moved an entire nation, and the Dutch football association took immediate action.
"After the incident the Dutch FA decided that there should be more respect for referees," says Jan ter Harmsel, a journalist and referee who runs a blog website for match officials.
"Only captains can talk to the referee now, other players would be booked immediately,"
Former Netherlands international player Ronald de Boer agrees that the fatal attack has had a big impact, but worries that the reaction by officials has been too strong.
"Football is emotion, and in a way the changes killed the game a little bit. Now yellow cards are shown for everything," the former Ajax, FC Barcelona and Glasgow Rangers midfielder told CNN, while acknowledging that players in Holland "moan too much."
"Certainly we have to pay attention to give a lot of respect to referees, starting with the parents in their education of their kids," said De Boer, who now works with Ajax's youth setup.
The Dutch FA (KNVB) sent CNN figures which showed that while yellow cards shown to players have not increased overall since the December 21 attack, the numbers of bookings for dissent to officials has almost tripled from 0.17 per game before December 21 to 0.48 each match since.
The new KNVB charter has a broad social backing, according to its press office chief Marloes van der Laan.
"After issuing an appeal on Facebook, KNVB headquarters in Zeist received a veritable deluge of emails and letters containing suggestions about how to improve the overall atmosphere surrounding Dutch football matches," van der Laan said.
"All these suggestions were considered, many were taken on board and some were adopted in the FA's action plan. In addition, on December 21, the KNVB issued a Charter titled 'No Football Without Respect.' The Charter listed no new rules, but provided for stricter enforcement of existing ones."
Harmsel, a youth referee in The Hague, believes the education of younger generations needs to be addressed.
"The Richard Nieuwenhuizen incident was a few months ago, but I heard about an abandoned under-eight match last weekend," he said. This time, the coach of one team took his players off the field in protest at a lack of protection from alleged opposition foul play.
The Dutch Organization of Soccer Referees, meanwhile, told CNN that little has changed as a result of the December 2 attack on Nieuwenhuizen, whose assailants began a pretrial hearing on Monday -- six teens and one of their fathers appeared in court charged with murder.
"Although awareness of the problem of violence in society in general and on the soccer pitch in particular was raised immediately following the serious accident, and although there was one weekend with no soccer for the non-professional leagues, by now things are back to 'normal,' " said the organization's secretary Willie Peijnenburg.
"Several actions of awareness raising are being prepared, but since the incident several referees have been attacked again, even in friendly matches."
In neighboring Germany, the situation is equally worrying: the country's 70,000-plus match officials are subjected to what they feel are increasing levels of violence.
Leading football magazine Kicker is running a series on increasing violence against referees and dwindling referee numbers nationwide, while the influential Der Spiegel wrote in December 2012 about a string of violent attacks against lower league referees.
The most serious of these came in September 2011 in Berlin, when Gerald Bothe was assaulted on the pitch for showing a player a second yellow card.
The parallels with the recent attack in Valencia are chilling. Bothe was unconscious for 10 minutes, swallowed his tongue, and was hospitalized for several days.
A study at the University of Tubingen, which interviewed 2,600 regional referees, showed that 40% had been threatened, while 17% said they had been physically attacked. Those are worrying numbers, particularly for young referees such as Max Klein.
At two meters tall, the 18-year-old towers above most players, but still admits to being intimidated by the frequent cases of violence against referees that he hears about on social networks.
"Of course it is a shock to a young referee to hear of cases like Valencia and Holland," said Klein. "There are a lot of cases here too. Since I started four years ago it has certainly gotten worse. You don't hear about it in the mainstream media because it happens in lower divisions, but a referee friend of mine posts it all on Facebook.
"Just the other day a player waited in the locker room and beat up a referee. So before you whistle a game, you think, 'Hopefully I don't whistle a rough lot today.' "
Herbert Fandel, the head of the German Football Association (DFB) referee commission, has acknowledged that violence is a factor in influencing dwindling referee numbers.
"The verbal and physical violence against referees is also a sign of our times, a mirror of our society. Values like respect and decency are too often kicked with the feet," Fandel wrote in the DFB's referee magazine. The DFB told CNN that it is compiling statistics with regional associations, and could not comment at the moment.
Klein is just a few months older than the hospitalized referee in Valencia. He too has already had encounters with violence on the pitch, abandoning one match between teams of 14-year-olds in Konigsdorf, near Cologne, when the two coaches ran onto the pitch and started a brawl.
Klein says corrective action will be needed soon -- 10 years ago there were 1,000 active referees in the wider Cologne area where he whistles, but now there are just 600, according to the DFB magazine. Overall referee numbers in Germany have been steadily decreasing, the DFB said.
"It would be tough to get a bodyguard for every referee," Klein says with a wry smile. "So I think the best way forward is to introduce monetary fines for teams. That would really hit the aggressors hard where it hurts most -- in their pockets."
The blame game
Former international referee Tom Henning Ovrebo, who received death threats long after a controversial European match in 2009, would also like to see strict punishments.
"All over Europe you can find a culture of harassment against referees," said the Norwegian, who was widely accused by media -- and former Chelsea coach Jose Mourinho -- of favoring opposition team Barcelona in the second leg of a Champions League semifinal.
In 2011, Mourinho -- by then coach of Real Madrid -- named Ovrebo in a list of referees he claimed favored Barcelona after his team lost another Champions League semifinal match to the Catalan side.
Ovrebo says such criticism is part of the problem in fanning lower-league violence.
"I think all promising young players and coaches try to copy their heroes. And when they harass and blame the referees during or after a game, the young players and coaches will also do so," said the 46-year-old, who retired from international level in 2010.
"And sometimes the media enhance the effect by showing everyone what a 'jerk' the referee is."
Ovrebo believes refs need to be better prepared to deal with verbal and physical violence.
"In my local association ... we teach them about the laws of the game and positioning, but little is done to prepare them for the mental demands."
Ovrebo, who works as a psychologist, says that recent research links violence in football with the supposed safety of belonging to a crowd.
"One thing we know from research on hooliganism is that people tend to 'de-individualize' themselves and become more a group member who follows the group norms instead of their own norms," he said.
'Respect and trust'
The English Football Association, meanwhile, has taken an innovative approach to stopping violence against match officials by introducing the "Respect" program at grassroots level, using online videos to promote "effective dialogue" with players
"It should be noted that player behavior in the Premier League has increased greatly in recent years," says Phil Dorward, head of public relations for the EPL and the body governing its match officials.
"In the past three seasons bookings for dissent have decreased by half. This has been the result of a lot of dialogue between all key parties."
European soccer's ruling body UEFA also has its own Respect program, spearheaded by former Netherlands international Clarence Seedorf and ex-leading referee Pierluigi Collina.
"There are a lot of meanings for respect on and off the field of play," Collina said at last year's launch. "Respect and trust between players and referees -- which makes the referee's job easier -- or respect for the players from the fans.
"Respect is the only way to get a bright future for football."
Giving up the whistle
World football's governing body is well aware of the potentially devastating consequences of alienating referees from the game at grassroots level.
"For anyone who has ever played a game at whatever level, it is always more frustrating to play without a referee," Massimo Busacca, the head of FIFA's referees department, told CNN.
"If you behave badly and in a threatening manner, this ruins the enjoyment for others, and could even lead people to quit the game."
That has been the consequence of Giner's early encounter with violence in European football.
"Refereeing was his dream," says his father. "For now, he will give up the whistle."