It's taken almost 20 years, but thanks to DNA testing, a trial for the suspect in the assault and murder of a nine-year-old girl has begun.

Eric Daudelin, 40, is accused of molesting and killing Joleil Campeau, who disappeared in June 1995, after telling her mother she was heading to a friend’s house near her home in Laval.

The girl walked through a wooded area near a small river and was never seen alive again.

A few hours after she went missing, a search party found Joleil's belt in the woods, and police found a ski mask and gloves.

It took four days to locate the child’s body, found when police drained the river. Rocks were placed on her body to keep it underwater.

In spite of questioning suspects, no one was ever charged.

Advances in DNA testing allowed police to reopen the case, the Crown explained in court Monday.

Daudelin was arrested in June 2011.

Now 40 years old, he would have been 21 at the time of the murder.

Police believe he sexually assaulted and killed Joleil.

Daudelin has all along maintained his innocence.

“At the beginning of the inquiry, he made a statement to the two investigators that went to see him and he disclosed an alibi,” said defence lawyer Gilles Daudelin (no relation).

The trial began Monday and is expected to last four weeks. It is subject to a partial publication ban. 

If convicted, Daudelin could be sentenced to life in prison with no chance of parole for 25 years.