Four years and four days have passed since the cogs of justice grudgingly broke their rusty hold on Dennis Maher's jail cell and allowed the wrongfully convicted Waste Management mechanic to walk free, 19 years after a Middlesex County judge sentenced him to life in prison for three sexual assaults he did not commit.

The diesel engine technician, welder and preventive maintenance specialist with Waste Management on Kondelin Road in Gloucester is married now, with a 13-month-old daughter and 2-year-old son, a house in Tewksbury and a new sports utility vehicle.

He goes fishing when it is warm, cogitates about what he will make for dinner, does not mind getting up at 3:30 a.m. to make it to work by 5 and calls his mother daily.

But Maher, 46, says there will never be a day when the recollection of almost two decades of imprisonment does not cross his mind.

"I was Walpole 40347," Maher said of his inmate number at the maximum-security prison in Walpole, "and I'll know that number until the day I die. I lost what I can never get back. I should be a grandfather by now. I've got a 1- and a 2-year-old, and I'll be in my 60s when they graduate high school."

Maher speaks well. He is not shy about sharing his experience, which he can outline in about 20 minutes, and has done so hundreds of times for complete strangers and media outlets as far away as Germany, Australia and England.

He begins his history in November 1983, when he was 23 and had just re-enlisted as a sergeant with the Massachusetts National Guard. Lowell police detained him Nov. 18 that fall, and he was charged with the rapes of two women, one in Lowell and another in Ayer, and the attempted rape of a third woman in Lowell. Two jury trials in the spring of 1984 convicted Maher of the crimes, and a judge sentenced him to life in prison without the chance of parole.

In 1993, while watching an episode of "Donahue," Maher saw lawyer Barry Scheck talking about the Innocence Project, a national organization dedicated to exonerating wrongfully convicted people through DNA testing.

Maher wrote to the Innocence Project, outlined the history of his incarceration and pleaded for any assistance Scheck or the Innocence Project's other lawyers could provide.

The New England Innocence Project took up Maher's case pro bono, and for eight years his lawyers worked to exonerate him despite being told that all evidence from his trials had been destroyed.

Then, in 2001, a law student discovered two boxes of evidence from the Lowell cases in the basement of a Middlesex County courthouse, including pants and underwear from one of the rape victims.

Testing of semen on the underwear revealed a genetic profile that excluded Maher. Shortly after testing was completed, a DNA slide from the Ayer rape case mysteriously showed up at the office of Maher's lawyer. DNA results from the slide also excluded Maher in March 2003.

After reviewing the DNA results, the Middlesex district attorney joined the Innocence Project in filing a motion to grant Maher a new trial and agreed to drop all charges against him.

"My lawyer called me on April Fool's Day and asked when I wanted to go home," Maher said. But 19 years of prison had honed his skepticism and it was not until the morning of April 3, 2003, when he was able to walk unshackled in public, that he celebrated as the Innocence Project's 127th wrongly convicted person to be exonerated.

Since then, 70 more innocent convicts have been freed, bringing the project's grand total to 197.

"If you look at the prison population, there are roughly 2 million prisoners in the U.S.," Maher said. "One percent of them are innocent. Ten percent of (those prisoners) might have DNA to exonerate them. That's 2,000 people."

So Maher has taken the Innocence Project's mission under his wing and traveled throughout the country, speaking at colleges, meeting with lawmakers and other officials, trying to convince states to change their DNA laws. He helped change DNA legislation in Maine last year and was in Vermont two months ago trying to do the same there.

"(The Innocence Project) is a pretty big deal in this country," Maher said. "It's just that a lot of people haven't heard of it."

Maher's dedication to Scheck's Innocence Project recently earned him the Erich Jenkins Life Changer Award at Waste Management's annual conference in Las Vegas.

Erich Jenkins was a former NFL player and vice president of a national fitness company who was killed when his vehicle was struck by a Waste Management truck in 2002. Jenkins believed in the power of one person to change a life and his mantra was adopted by Waste Management.

Working with the Innocence Project "makes me feel good, because I have an impact on other exonerateds' lives," Maher said. He added that the award was not something he was seeking, but that it feels good to be recognized.

But still Maher's life has not - and never will - return to normal. He has filed two $20 million lawsuits - one against the city of Lowell, the other against the officer who arrested him in November 1983.

That man, Edward F. Davis, is now Boston's police commissioner. According to Maher's lawyer, Robert Feldman, Davis falsified police reports in order to frustrate Maher's alibi. Furthermore, Feldman cited Davis' role in influencing one of the victim's identification of Maher during a lineup at the police station by placing a chair in front of Maher to single him out.

A spokesman for the Boston Police Department said Thursday that Davis would be unable to comment on Feldman's claims because Davis is too busy with his duties as commissioner.

Lowell Assistant City Solicitor Brian Leahey could not comment on pending litigation, except to say that he disagrees "with the allegations set forth in (Maher's) complaint."

The victims, Maher says, are not to blame for the 19 years he lost.

"They have been affected three times," he said. First, he noted, were the nights of the assaults. Second were the court trials and third was when the Innocence Project freed him and the victims came to the realization they had helped put an innocent man in prison and their real attacker was still at large.

In the coming years, Maher prays more states will change how suspects are identified by police, witnesses and victims.

"I just want them to open their eyes," he said. "This stuff really happens. Very seldom do you see what happens when an innocent person goes to prison, and a lot of people don't want to hear any of that."