His cousin, Amin Speakes, sat in jail for more than two years waiting to be tried for a 2009 slaying, partly because of what detectives said Rainey had told them during one of those sessions: that he saw Speakes shoot the victim.
Rainey, now 20, told the Daily News last week that he endured nearly 20 hours in police custody as detectives shoved, threatened and yelled at him while he breathed a detective's cigarette smoke. Starving, Rainey said he signed a police statement fingering his cousin without reading it - just so he could get out of there.
"They made it seem like I said something I didn't say. I don't like how that went," said a downcast Rainey, who maintained he never told the detectives he saw his cousin shoot the victim.
Speakes was acquitted in February 2012 after his jury saw surveillance videos from a gas station and a hospital that showed that he and Rainey were together at the time of the slaying and nowhere near the crime scene.
Defense lawyers say situations like Speakes' could be avoided altogether if Philadelphia joined the growing number of police departments - an estimated 850 in the United States - that videotape interrogations.
"It's foolish that they don't videotape," said defense lawyer Samuel C. Stretton. "The only reason I can surmise is they do not want anyone to see the give-and-take that results in the statements."
The blackout in interrogation rooms undermines the credibility of criminal trials and the police department, legal experts say.
"The inference is they are using techniques that would be abhorrent to the public and to judges," said lawyer Ronald Greenblatt, chairman of the Philadelphia chapter of the Pennsylvania Association of Criminal Defense Lawyers.
Philadelphia police spokesman Lt. John Stanford said Police Commissioner Charles H. Ramsey supports recording interrogations, just as he did as chief of police in Washington, D.C. The department is in the "infancy stages" of working with the city and others on a new policy for recording interrogations that will spell out how suspects and witnesses are to be treated, Stanford said.
But logistics, money and a state law that requires that permission be obtained from those being recorded are hampering the department's goal, he said.
"It's not as easy as throwing a camera in a room. There are a lot of logistics that have to be worked out," Stanford said.
John McNesby, president of the Fraternal Order of Police, said he believes that recording interrogations "would be a useful tool" for police but doubts the department has the money.
"They can't get to homicides because they don't have running cars," he said. "They don't have the proper computers" and their offices are often infested with lice, bedbugs and roaches, McNesby said.
"That would be a wish list for the future, but now they don't have the means or the money," he said of filming interrogations.
Greenblatt said the Police Department has been dragging its boots and spinning excuses for years on the videotaping issue.
"Every major jurisdiction and most of the minor jurisdictions in Pennsylvania videotape now, and they [Philadelphia] don't. So they're just coming up with reasons to delay," he said.
"The fact that they don't is suspect, and what it does is take away from people's trust in the system. Jurors are not stupid. They know how inexpensive videotape equipment is."
Paul Conway, chief of the Homicide Unit and Special Defense Unit at the Defender Association of Philadelphia, said the only filmed interrogations he could recall were many years ago and only of defendants reading written statements that had been taken before the cameras were turned on.
They had the look of prisoner-of-war propaganda videos, he said.
"If you're going to do it, you ought to do it right, Otherwise, you don't get the whole picture," he said. "It puts your credibility up in the air" not to record the entire interrogation process, he said.
Gary Server, a city defense attorney for 24 years, said the Police Department would help itself by recording interrogations.
"We are constantly accusing them of engaging in some sort of impropriety, putting words in people's mouths, not feeding them, not letting them talk to their families," he said. "That could end if we saw what was going on."
Stanford said detectives work hard to solve crimes and that it is unfair for anyone to make blanket statements about them engaging in misconduct. He encouraged anyone who believes he was mistreated during an interrogation to file a complaint with Internal Affairs by calling 215-685-5056.
"One of the things the commissioner has been very clear of since he's been here is that he's looking to rid the department of any type of behavior that is not appropriate," Stanford said. "Give us the opportunity to investigate it, because by all means, we will."
Marissa Bluestine, legal director of the Pennsylvania Innocence Project, said the reality of false and coerced confessions cry out for cameras being in interrogation rooms.
"Police departments feel like they are being blamed and attacked. But it's not about blame; it's not about bad actors. It's about bad methods. Our position is: get on board. Let's do it. We'll help in any way we can," Bluestine said.
"We have a common goal - getting the right guy."
'It's being competent'
New York City, Los Angeles, Chicago, Houston, Phoenix, Dallas, San Diego, Washington, D.C., San Francisco, Detroit and San Jose, Calif., are among the cities that videotape interrogations.
"It's more work. It's more organization. But you know what? It's being competent. Everybody has accepted the same practices," said Los Angeles Robbery-Homicide Detective Barry Telis.
In San Diego, taping interrogations in homicides and other crimes goes back to the 1980s when VHS tapes were in use, said homicide Lt. Jorge Duran.
Today, digital recordings are used to make it "easier for us to present the case and bring forth the best evidence that we have as far as what the witness said," said Duran. "There's no ambiguity."
In Philadelphia, trials often end with the process coming under fire due in part to speculation about what occurred during interrogations.
Rainey doesn't like to talk about the interrogation that he said resulted in detectives fabricating a statement they attributed to him.
The room was small and cold, and one detective smoked up the air with a cigarette, he recalled. Another detective repeatedly shoved him back in his chair whenever he rested his head on the table. " 'You know you f----d up, right?' " he recalled one detective saying.
"It changed me. I should have read it before I signed it," said Rainey, who has a learning disability. "They should record the stuff in there so they can see what really happens in there. They don't always tell the truth."
His family is planning to sue the city over his cousin's arrest and confinement in jail for two years, four months.
"They did him an injustice; they did my family an injustice. No one told me where he was or what they were doing with him," said Vernell Rainey, who is Rainey's aunt and Speakes' grandmother.
Rainey's father, Wayne Rainey, is also bothered by the episode.
"I feel angry, a little embarrassed and also mad at the system," he said. "Had they done their job properly, they might have had the right people."
On Twitter: @MensahDean