MONTREAL -- A judge on Monday found a man guilty of second-degree murder for the stabbing death of his girlfriend in 2014.

But the man, Yves Nadeau, has an IQ between 45 and 50, according to experts who evaluated him at the judge's request. Any result below 69 is considered extremely low. Nadeau had been incoherent following his arrest and at court appearances, but the experts ruled he was not mentally ill. His defence said that evidence showed he had the mental capacity of an 11-year-old.

In 2014, Nadeau lived in a small apartment with his girlfriend, 62-year-old Louise Girard. He stabbed her several times and attempted to strangle her, the court heard. Police found a knife in the apartment, blood and DNA evidence that pointed to Nadeau as the culprit.

Nadeau didn't understand why he was being arrested. On the stand, he didn't understand concepts like taking an oath or what his legal rights were. But he had been found mentally competent, the judge said before finding him guilty of Girard's murder. As a security guard handcuffed him, he smiled and waved to his family.

Nadeau's lawyer pleaded with the judge. He hoped the court would allow his client to live with his elderly parents for now. A man with the mental age of a child should not be sent to prison, he argued. The judge declined the request.

Nadeau's defence will try to convince the court to find him criminally insane -- after the trial, which is permitted under an obscure section of the criminal code.