Rebecca McAlister has waited 18 years for her son, Michael, to walk out of prison. Tomorrow, she gets her wish, but the moment will be bittersweet.

The Michael McAlister who will gain his freedom is an angry man, outraged at a system that left him incarcerated for attempted rape even though the prosecutor and lead detective came forward years ago and said he likely was innocent.

All that time, McAlister got to know his two young daughters, and now a grandson, through letters and photographs. To his mother, he "has done someone else's time. It's really rotten to put politics ahead of someone's life."

But Rebecca McAlister is thrilled that her son will walk out of Lunenberg Correctional Center near Richmond, even if it took mandatory parole to bring him home. "I'm just so excited," said McAlister, who plans to make her son's favorite meal tomorrow night -- filet mignon, with all the trimmings.

It has been a highly unusual journey for McAlister, 48, a carpenter who was convicted in 1986 of being the masked attacker who tried to rape a young mother. The prosecutor, former Richmond commonwealth's attorney Joseph D. Morrissey, told the judge that McAlister was guilty "pure and simple."

New evidence later emerged about another suspect, and the victim's identification of McAlister was called into question. Both Morrissey and former detective Charles M. Martin signed sworn affidavits saying they might have locked up an innocent man.

But efforts to exonerate McAlister went nowhere. Under Virginia law at the time, courts could not consider new evidence of innocence if it was brought forward more than 21 days after sentencing. In 2001, lawmakers changed the law to allow DNA evidence to be introduced at any time, but there was no DNA in McAlister's case.

Still, Morrissey and Martin testified on McAlister's behalf before the Virginia Parole Board, and their sworn affidavits were submitted with a clemency petition filed with Virginia Gov. Mark Warner (D) in 2002. The parole board repeatedly declined to release McAlister, and Warner rejected the petition.

A spokeswoman for Warner declined to comment yesterday, and the current commonwealth's attorney in Richmond, David Hicks, did not return telephone calls. The victim in the case could not be located.

The General Assembly recently expanded the Virginia law to allow courts to consider non-biological evidence of innocence long after a conviction. But by the time that law took effect July 1, the date of McAlister's release was approaching. He was sentenced before Virginia abolished parole in the mid-1990s, so under the sentencing system in place at the time, he would be freed after 18 years.

The 18 years expire tomorrow.

The case spotlights a growing national debate over faulty eyewitness identifications. DNA testing has cleared numerous prisoners nationwide, and mistaken eyewitness testimony has been blamed for most of the errors.

Vanessa Potkin, a staff attorney with the New York-based Innocence Project, which seeks to exonerate wrongly convicted people through DNA evidence, said McAlister's case is particularly egregious.

"It's extremely rare what this prosecutor and detective did in coming forward, and the fact that you would have people ignoring this evidence or turning a blind eye is extremely troubling."

McAlister consented to an interview from prison through his attorney, but Department of Corrections officials declined to make him available yesterday. In a phone interview this month with the Richmond Times-Dispatch, McAlister said being away from his family was the hardest part of being imprisoned.

"I've been filled with hatred," McAlister said. "I hate to say it. But that's, that's what's gotten me through it. It's the last you think about before you go to bed and the first thing you think of in the morning as soon as your eyes open: 'This is real, and I did not do it, and they know I did not do it and here I am.' "

McAlister's attorney, Christopher Amolsch, said McAlister is "understandably filled with an enormous amount of rage. He's mad that he got convicted but even more angry at a system that basically permitted him to stay incarcerated for a crime he didn't commit."

When detectives first interviewed the woman the night of the Feb. 23, 1986, assault, she said the assailant had a stocking over his face -- which she pulled partway up during the attack -- and wore a plaid shirt that was red, white and another color. Detectives learned that the sketch resembled McAlister, who lived nearby and had convictions for indecent exposure and larceny.

When a detective came by to take a photo, McAlister happened to be wearing a red, white and blue plaid shirt. The woman identified McAlister as the attacker from photographs, and at the trial, she identified his shirt as the exact shirt worn by her attacker.

But the prosecutor and detective began developing doubts when they learned that other detectives had followed another man, a rape suspect, to the woman's apartment complex a few weeks before the attack. That man was later convicted and sentenced to life in prison for another rape in which he wore a stocking mask. He has denied involvement in the attempted rape and abduction for which McAlister was convicted.

McAlister's mother said he has lined up a job as a telemarketer and plans to live with her in Richmond. He also still hopes to pursue efforts to clear his name.

Staff writer Maria Glod contributed to this report.

A prosecutor and detective said he could be innocent, but Michael McAlister spent 18 years in prison.