DETROIT (WWJ) — At first glance many assumed the drug dealer living with a 12-year-old runaway in a burned-out apartment building was guilty — of something — when she turned up dead.

But after 20 years in prison, the Detroit man who has been locked up for the brutal murder of his young companion is holding out new hope that he will be exonerated. And he has support from high places.

On January 20, 1996 — 11 days before his 24th birthday — drug dealer Lamarr Monson emerged as a suspect in the murder of 12-year-old runaway Christina Brown, who was found dead with massive head trauma inside their apartment on Detroit’s west side.

She had also been stabbed, beaten and strangled. According to a report from the Detroit Free Press at the time, Monson had allegedly argued with the young girl who was selling crack and marijuana with him shortly before her death.

The night Brown was killed, a neighbor told police she heard Monson drive up, then leave in a rush 45 minutes later.

Piling on the evidence, another neighbor told  police Monson banged on his door and asked him to call for help because his girlfriend was lying on the floor in a pool of blood. Monson later confessed to killing her, police said, while family members said his confession was coerced.

Though he was convicted, a witness has now come forward claiming Monson is not the killer, and that she knows who is responsible for the brutal murder. New physical evidence has also allegedly emerged.

With these factors, Monson is hoping there could be movement this week in his fight to clear his name.

Does he have grounds for a new trial? Thomas talked to veteran TV reporter Bill Proctor, who now works as a private investigator, and Proctor says the woman who claims she knows for sure he is innocent has passed a polygraph test. “I believe him,” Proctor says of Monson.

[View court documents detailing the case]

In 2012, an alleged eyewitness came forward and fingered the man she said was responsible for Brown’s death. The woman was new to the city, also living in that apartment building and buying crack. Her story is that she bought drugs with a boyfriend from Brown that fateful night, they smoked it, he went back several times for more drugs on credit — and on the last visit he allegedly stayed in the apartment with Brown for an extended time.

“When he came back, his appearance was shockingly different,” Proctor said. He was literally dripping in blood.

She says he threatened her into silence at the time, but now the woman who believes her ex is the killer wants to testify on Monson’s behalf.

So, what was Monson’s role? In an exclusive interview from prison, Monson gave Thomas his account of finding Brown in the apartment that fateful day.

“She was alive when I found her,” he said. “She called my name out. I ran from apartment to apartment asking people to call the EMS. There was no one in the apartment who had a telephone …”

He added he drove to his sister’s house to find a working telephone, and came back to try to console her and tell her to “hold on” while they awaited emergency personnel. He said he did everything he could to assist her while they waited, including doing CPR.

He stayed by the side of the 12-year-old runaway who had allegedly convinced people in the neighborhood she was 17, until help arrived. Then he cooperated with police.

Proctor added Monson clearly tried to get help for his girlfriend while she was on the floor, bleeding, which isn’t the action of a killer. “He did not leave the scene,” Proctor pointed out.

Monson, who was working as an electrical apprentice while “supplementing his income” as a drug dealer, said he never thought he would be charged with killing the child he lived with.  “I was just devastated by the situation,” he told Thomas. “To have it turn on me is just something I never expected.”

He’s spent his time in prison researching the law and putting together appeals.

If he goes free, Monson said he would thank God, spend time with his now-26-year-old daughter and young granddaughter. But he says he would not be bitter or resentful. “I’m just grateful … I just would count it as a blessing,” he said.