But the Mexican photojournalist didn't try to enter any kind of protection program, despite the threats he said he'd faced, a friend of Espinosa's told CNN.
"He didn't trust them," the friend said.
Now the 31-year-old photojournalist and four others are dead -- found slain Friday in the Mexico City home
of an activist who'd also criticized the government in Espinosa's home state of Veracruz.
Authorities haven't released the identities of the other four victims. All five of them had been shot in the head, prosecutors say.
Espinosa's friend, who asked to remain anonymous out of fear for his own safety, said the group was found dead in the southern Mexico City home of Nadia Vera.
Vera was an activist who was friends with Espinosa. She'd participated in student movements and criticized government officials in the past, the friend said.
The case has drawn sharp condemnation from major Mexican media organizations and struck a nerve in a country where press freedom and violence against journalists have become growing concerns.
"The murder of Ruben Espinosa marks a new peak in violence against the press in Mexico," the press freedom advocacy group Article 19 said in a statement
And it's not just Espinosa's death that's sparked concern.
Protesters in Mexico City over the weekend demanded justice for Espinosa and the four others who were found slain along with him -- all women.
"Four women were killed, but the headlines do not say anything about them," some demonstrators chanted, according to CNNMexico
Magazine, photo agency: Threats should be investigated
The directors of Proceso magazine and the Cuartoscuro photo agency, who employed Espinosa, are calling for authorities to investigate threats they say the photojournalist had received
"Ruben told me when I saw him that living with this, with threats on top of you, you cannot live in peace, you cannot do your work in peace, you walk in the streets thinking about who is following you, who is looking at you," Cuartoscuro editor Moises Pablo said.
In June, Espinosa told Article 19 that he noticed he was being followed in several locations and given threatening looks. At least one of the people who appeared to be following him snapped photos of him. Espinosa told the advocacy group that he also saw men standing outside his home in Veracruz, and who gave him menacing looks before walking away.
"I had to leave because it was not a direct threat, but I got the message," Espinosa said in the last interview he recorded with the outlet RompeViento. "It was just recently when students were attacked and brutally beaten with machetes. In these situations, we can't do less with any type of aggression or intimidation because we don't know what might happen. Veracruz is a lawless state."
Investigators in Mexico City say
the photographer's family members told them he came to Mexico City in search of employment. They say they're treating the killings as a case of homicide and robbery, while keeping other lines of investigation open.
But Espinosa's friends and colleagues say threats Espinosa received should also be part of the investigation.
They also say it's important to note Espinosa's history of covering anti-government protests in the state of Veracruz.
"The violence of which Espinosa was victim is publicly known of by the authorities charged with protecting journalists in Mexico," Article 19 Mexico Director Darío Ramírez said in a statement. "This homicide puts the situation in Veracruz, and the negligence of local authorities in providing protection, sharply into focus."
Governor: Killings were 'abhorrent acts'
In the past five years, 13 journalists have been killed in Veracruz, which has seen some of the deadliest violence in Mexico's battle against drug cartels.
Vera, whose apartment was the site of Friday's slaying, was a vocal critic of Duarte's administration. In a video posted by RompeViento
, she criticized his handling of the journalists' deaths and other violence in the state.
"How many journalists have been murdered, and nothing has happened?" she said. "How many students, activists, human rights activists have been murdered, kidnapped, disappeared? We have an incredibly high rate of missing people, no? But it also has to do with the character of who is currently in government."
Duarte has vowed in the past to step up efforts to protect journalists in Veracruz.
"There is no democracy that evolves without freedom of speech and thought," he said after authorities pulled the bodies of three dismembered photojournalists from a canal
in the city of Boca del Rio in 2012. On Monday, he described the killings in Mexico City as "abhorrent acts"
and called for authorities in the capital to investigate.
But violence targeting journalists in the state has continued. On Sunday, a newspaper in the town of Poza Rica was attacked, Mexico's Human Rights Commission said in a statement
And the director of Proceso and journalists who work in the state say remarks the governor reportedly made at a recent meeting, accusing journalists of ties with organized crime, have them wondering how committed he and other Mexican officials are to protecting members of the media.
"Behave yourself," Duarte said, according to quotes of his comments widely cited in Mexican media. "Because we are going to shake the tree, and many bad apples are going to fall."