AUGUSTA — A man convicted in February of killing Franco-American singer Jean Paul Poulain was back in Kennebec County Superior Court this morning pleading guilty to a charge of criminal mischief.

Mathiew D. Loisel, 22, who is serving 30 years in prison for Poulain’s murder, was accused of damaging a window at MaineGeneral Medical Center in Augusta on Feb. 5, 2007, which was several months before Poulain’s murder.

Justice Nancy Mills sentenced Loisel to 30 days on the criminal mischief charge, to be served concurrently with the murder sentence.

Loisel, who has a lengthy history of mental illness and hospitalizations at the state psychiatric hospital in Augusta, went with another man to rob Poulain at his School Street apartment in Augusta on April 24, 2007. Loisel told police he shot Poulain.

Poulain died of his wounds in an ambulance but not before naming the men who did it. Loisel is serving his sentence at the Maine State Prison in Warren.