(CNN) -- Seventy seconds: That's how long a North Carolina family says it took for things to go horribly wrong as they sought police help dealing with their mentally ill son.
Keith Vidal, 18, died Sunday. According to CNN affiliate WECT, he was just shot 1 minute and 10 seconds after a third law enforcement officer showed up at his Brunswick County home.
The three officers all were from different jurisdictions, and family members say that the third officer -- who came from a nearby city -- turned what had been an improving situation into an unnecessarily aggressive encounter that ended in their son's death.
"There was no reason to shoot this kid," the teen's stepfather, Mark Wilsey, told WECT on Monday. "They killed my son in cold blood. We called for help, and they killed my son."
Although the state Bureau of Investigation is looking into the shooting, the chief prosecutor for the state's 13th Judicial District, which includes Brunswick County, says it's way too early to characterize what happened.
"I think that we can certainly understand why this family is upset right now," the Wilmington Star-News newspaper quoted District Attorney Jon David as saying. "They just lost a child, and certainly my thoughts and prayers are with them. But what they want from this office today is justice, and I intend to give them exactly that."
CNN first learned of the shooting through an iReport sent by a family friend. The iReport received more than 50,000 views in 24 hours.
The incident happened Sunday afternoon when the mother and stepfather of the Boiling Spring Lakes man called police. According to stepbrother Mark Ryan Wilsey, Vidal had schizophrenia and "was having an episode," and his parents wanted police to subdue him so he could get help.
"He's not doing very good. You've got to get him someplace," a man who identified himself as Vidal's stepfather said on a 911 call, a copy of which was obtained by WECT. "He wants to fight his mother. ... She's scared to death of him right now."
The caller said that Vidal "won't take his medication" and that his family has had "to put him in before, (and) he's getting real bad again."
"He's just, he's not right," he said.
Two officers arrived and began talking with Vidal, according to CNN affiliate WWAY. The situation was relatively calm until a third officer -- a detective from the nearby city of Southport -- arrived, the family said.
"Everything was going good," Mark Wilsey said, according to WWAY. "Then this fat cop from Southport walks in the room, walks around the corner, says, 'We don't have time for this. Tase that kid now. Let's get him out of here.' "
The stepfather said Vidal tried to run but was struck with two Taser charges and fell backward. He said the first two officers to respond got on top of Vidal.
WECT attributed a slightly different accounting of events to Mark Wilsey. In that retelling, the stepfather said officers had pinned Vidal to the ground after he had been tased and one of the officers said, "We don't have time for this" and shot his stepson.
Seventy seconds after the third officer arrived, WECT reported, citing police records, police radioed that they had had to shoot the teenager in self-defense.
Mark Ryan Wilsey, who was not at the house but rushed there in an "absolute panic" and claimed that police restrained him, said his family is outraged by what happened and determined to get justice.
"We want the truth to be out there," he said. "We don't want the good ole cops system to play out something that ain't the truth."
Authorities have not released the exact sequence of events, including how and by whom Vidal was shot.
A Southport officer has been placed on paid administrative leave in connection with the shooting, Police Chief Jerry Dove said Tuesday. Authorities have declined to say whether he was the officer who shot Vidal.
The Brunswick County sheriff's deputy sent to the scene has been "cleared," office spokeswoman Emily Flax said. A review conducted by its Office of Professional Standards found that the deputy did not violate policy, Flax added.
Boiling Spring Lakes Police Chief Brad Shirley said the same thing Tuesday of that department's officer, who was the first to arrive on the scene. The department said in a statement that, after an "internal review," it concluded that the Boiling Spring Lakes police officer who responded did not violate department policy or state law.
Neither the district attorney nor the state Bureau of Investigation returned messages seeking comment Tuesday.
CNN iReporter Anthony Owens, whom Mark Ryan Wilsey described as a good friend of the family's, described Vidal as a slight young man who was never violent despite his mental illness.
"All he wanted to do was play drums," Owens said. "He was so awesome."
The late teen's stepbrother said he did everything with Vidal -- hunting, fishing, sports and more -- describing him as a "good kid."
"He was my little buddy," Mark Ryan Wilsey said.
Owens said the incident highlights the need for more understanding and awareness of mental illness.
"I was devastated by the news and am desperate to find some kind of good that could come from this horrible situation," Owens said.
Mark Ryan Wilsey offered a similar sentiment, saying his family hopes to start a foundation to help the mentally ill like Vidal.
"We're uniting together, and we're going to make this go public," he said of the family's collaboration with Owens. "Because the way my brother got treated ain't right."
CNN's Tina Kim, Greg Botelho, Chris Youd and Katie Hawkins-Gaar contributed to this report.