Richard Henry Bain called the station from the infirmary at the detention centre in Rivières-des-Prairies, in eastern Montreal.
The radio station said Bain spoke to one of their reporters for nearly 40 minutes but didn't want to answer questions about the shooting.
He's accused of killing lighting technician Denis Blanchette, 48, while Marois was giving her victory speech inside the Metropolis concert hall on Ste. Catherine Street in downtown Montreal.
Bain's lawyer, Elfride-Andrée Duclervil, said she's surprised her client was able to make the call.
"I found that very strange. I thought how it was possible. My client is detained. He's in a medical wing at Rivières-des-Prairies. It's difficult for him to get in touch with me at times because he doesn't have access to the phone all the time," Duclervil said.
"To find out that he was able to call, it was difficult to understand."
The radio station said Bain wanted to talk about a plan to turn Montreal into a city-state. He told them it was a plan sent to him by God for peace on the island.
Duclervil said her client saw a psychiatrist on Tuesday and the doctor told her Bain is not well.
The lawyer said there are even questions as to whether he'll be fit to stand trial.
Besides first-degree murder, Bain is charged with 15 other crimes, including three counts of attempted murder, arson-related offences and a handful of firearms violations.
His next court appearance is scheduled for Oct. 11.