MONTREAL--The founder of the iconic Cosmo restaurant was being mourned on Sunday, as his son is charged with second-degree murder.

Police were called to Hufford St., a small, residential street in St-Laurent at about 3:30 a.m. on Saturday, where Tony Koulakis’s body was discovered. The victim founded the iconic and well-loved Notre-Dame-de-Grace greasy spoon diner.

“A member of the family was worried about the condition of the 86-year-old man, so he went to his residence and found him lying on the floor with wounds to his upper body, caused by a sharp object, possibly a knife,” said Montreal police spokesperson Raphael Bergeron.

"The motive of the (incident) is still to be determined by the investigators,” said Bergeron.

Police arrested Johnny Koulakis, who appeared at the Montreal courthouse Sunday handcuffed in a white t-shirt as he was charged with second-degree murder.

The Crown objected to his release, so he will remain behind bars until Tuesday, when his defence lawyer Charles Montpetit will decide if they will request a date for a bail hearing.

Neighbours said the man, in his 40s, suffered from drug problems and was unstable and volatile.

Visitors to “The Famous Restaurant” Cosmo, at 5843 Sherbrooke St. West, on Sunday morning left bouquets of flowers and messages of condolences addressed to the Koulakis family. The restaurant was open for business with Nikos, Tony’s other son, working. Nikos Koulakis preferred not to comment on his father's death.

Though the family patriarch retired in 2002, loyal customers never forgot his larger-than-life personality, that made him as his calorie-rich food the subject of documentary film Man of Grease by local filmmaker Ezra Soiferman.

“I was floored (by the news),” said passerby Jesse Brigden. “I’ve known Tony for a long time; I’ve been eating here for 20 years. He was just a really sweet old guy who took a lot of pride in his business.”

Brigden and his wife Melanie came from their Verdun home to lay a bouquet and pay their respects at the famed eatery that gives visitors not only a taste of home cooking, but of the Greek family’s home, itself.

“It’s kind of like coming to eat at somebody’s house. There’d be arguing, there’d be cigarettes, there’d be heated discussions but it was always interesting and they were always really friendly,” Brigden’s wife Melanie said. “They were good people. I can’t believe what happened to him after the life he’s lived.”

“He was a really unforgettable character. Very tragic. Just seeing the flowers here shows people's outpouring of emotions. It's very, very touching,” said customer Scott Macleod.

The crime scene left Koulakis’s Saint-Laurent neighbours in shock.

“I saw the old man last night. We were talking -- he had a coffee, I had my coffee. I don't know what happened during the night. I just woke up with the cordon all around,” said one unidentified neighbour.

Neighbours added that the son was known to have serious issues and had caused problems on the street before.

“(He was) verbally assaulting people… like, 'I'm going to f-ing kill you,'" said neighbour Patrick Angar.

Another neighbour, Silvana Kabalan, said she tried to warn the elder Koulakis his son needed help.

“Take care of your son,” she recalled telling her neighbour. “If the police send him to a hospital, leave him there.

You're going to save him. He said, ‘Yes, but he's my son. I feel sorry about my son.’ (I said,) ‘No, you don't have to feel sorry about your son, you'll help him.’ What can I say? It's his father.”

Koulakis’s death is Montreal's 12th homicide of 2013.

View the trailer for Man of Grease here