Quebec City police say a man they arrested in 1995 spent five years in jail for crimes he did not commit.

Simon Marshall confessed to a series of sexual assaults but police now say DNA evidence proves he was innocent.

At the time, investigators with the then Ste-Foy police force thought they had the man responsible for more than 30 sexual assaults.

Simon Marshall

Marshall, who was dubbed the "Ste-Foy rapist," confessed and pleaded guilty. The man, who his lawyer says has "behavioural problems", was convicted and spent five years in jail.

Arrested again after release

In 2003, soon after his release, Marshall was arrested in relation to three more sexual assaults.

He again confessed, but DNA tests cleared him of the crimes. Quebec City police chief Daniel L'Anglais decided to use the same DNA evidence to review Marshall's 1995 conviction.

The Sûreté du Québec was called in to oversee the process in the interest of transparency.

The DNA evidence proved that Marshall had not committed the crimes in question.

"Today I announce that Mr. Marshall is not guilty of those crimes," L'Anglais told reporters Wednesday.

L'Anglais says he doesn't really know how Marshall came to be convicted in the first place. DNA evidence collected in 1995 was never tested.

L'Anglais says the police department is not solely responsible for the error. "We have prosecutors, we have attorneys, we have psychologists, but remember Mr. Marshall said: 'I am guilty.'"

Lawyer thought client was guilty

Even Marshall's lawyer believed his client was guilty. Jorge Amijo represented Marshall when he was sentenced, and says Marshall fit the description provided by the victims.

"It all matched. The height, the weight, the way he acted," Amijo says.

Quebec's Public Security ministry says it will review Marshall's case and take vigorous action if it finds the investigation was mishandled.

As for having Marshall officially and legally cleared of the crimes, that decision would have to be made by a judge.