Washington (CNN) -- Christopher Winfield said he tried to raise the alarm about an alleged thrill-kill cult inside the U.S. military in Afghanistan but that his calls went to voice mail and his warnings were ignored.
Winfield described to CNN's Chris Lawrence his repeated attempts to warn the military about what was going on in the unit in which his son, Spc. Adam Winfield, was serving.
Winfield said his son, serving with a Stryker Brigade, learned that some fellow soldiers were killing civilians for sport, collecting body parts of their victims and taking photos of their exploits. And the father feared his son would be killed by his squad leader and other fellow soldiers if he tried to stop them.
"We should be the good guys fighting the bad guys," Christopher Winfield said Thursday at the suburban Washington offices of the law firm handling his son's defense. "We shouldn't be the bad guys."
In the quiet of a small conference room, Winfield -- a former Marine himself -- appeared to choke up as he watched video obtained by CNN's Special Investigative Unit of his son being questioned by Army interrogators.
His son is accused of killing one Afghan civilian. He admits he fired his rifle but claims he purposely aimed high and missed. Other soldiers face three murder charges and a variety of drug and other offenses.
"He looks beat, worn down," Winfield said about his son. He talked about how Adam always loved the military, even as a child choosing a military uniform for Halloween. "It's something he always wanted to do. He thinks it is an honorable thing."
Feeling pressure to participate in the killings and fearing for his own life, the son asked his parents in Cape Coral, Florida, for help.
In a Facebook exchange with his mother, shared with CNN, Adam Winfield said he was told: shut up ...or else.
"They planned and got away with murder once already -- I'm sure they could do it again. They don't want to go to prison," Adam Winfield wrote in one message.
"Do this: Tell them that you won't tell. Just ask for a transfer or something," his mother replied.
"It doesn't work that way Mom. You can't just ask to move -- we're already short-handed as it is," the soldier wrote back.
The father told CNN he reached out to an Army hotline and a member of Congress but was shunted to voice mail both times and never got a response.
The father did speak to a staff sergeant at his son's home base, the command center at Fort Lewis in Washington. He received what he described as a brushoff and was told his son should try to avoid the soldiers and wait until he cycled back to the United States.
"I told him the whole story: Adam is in Afghanistan and there is apparently a rogue sergeant that is killing innocent people and he is threatening my son and you need to get him out of there, do something," the elder Winfeld said of his conversation.
But the Fort Lewis contact said Adam should lie low, according to Christopher Winfield.
"He said, 'Stay away from the staff sergeant, and keep your head down and when you get back in four months, you can report it in safety,'" Christopher Winfield said. "My jaw hit the floor when I heard that, and it's just, 'You gotta be kidding me,' and he said, 'That's all I can do.'"
The Army is investigating the call, CNN has learned, looking at who received Winfield's warning of a possible war crime underway, and what happened to follow it up.
"We take what the father says very seriously. We know for a fact that he did call, and phone records prove the first call to Fort Lewis headquarters lasted seven to eight minutes. The commander at Lewis-McCord started an immediate investigation. He also called Army CID (criminal investigation) as well, they've started a separate investigation into the calls," an Army official said.
Adam Winfield's attorney Eric Montalvo said the Army inspector general also told Christopher Winfield that nothing could be done and that his son should lay low.
But spokesman Col. Thomas Collins said the Army has not yet found evidence that shows the elder Winfield called the Army inspector general.
The Army inspected the phone records of the Winfield family, with their consent, and determined that Christopher Winfield mistakenly called the inspector general of another federal agency, not the inspector general of the Army, Collins said.
"The Army remains committed to determining the facts of this issue," he said.
Montalvo says Adam fell into the middle of a serial-killer cult, what he described as "a culture of terror, fear and death."
"The Army is standing at the precipice of one of the most tragic circumstances they have ever encountered as an institution," Montalvo said. "They have a small opportunity to make this right."
Montalvo and others worry that if photos are made public of the killings and the mutilations of the bodies, it will eclipse reaction to abuses at the Iraqi prison Abu Ghraib, in terms of international outcry and negative feeling against the U.S. military.
For Christopher Winfield, each day churns up questions about whether he -- or his son -- could have done more to intervene, and to stop the killings.
"It's easy for someone to sit in a safe area, you know back here in the States to say that," Christopher Winfield said. "But when you are put in that kind of position where you have the good guys threatening to kill you and the bad guys threatening to kill you and you are stuck in the middle and you are 21 years old and you've got this monster of a man, 6-foot-4, 245-pound psychopath sergeant that is controlling your every move then, no, I don't think he could have done anything else."
Meanwhile the Winfield family -- the mother and father in Florida and the son held at Fort Lewis -- await word of the Army investigation and a Article 32 hearing set for next month that will determine whether a court martial will follow. But at least the family is relieved that Adam made it home alive.
"You have the Talilban trying to kill you and you have your own guys threatening to kill you," the elder Winfield said. "He had no chance and we were scared to death."
CNN's Scott Zamost, Drew Griffin and Kathleen Johnston contributed to this report.