MONTREAL -- The Crown's evidence against ex-Montreal mayor Michael Applebaum is weak and depends on witnesses who testified against him to "save their own skins," his lawyer said in closing arguments on Monday.

Applebaum has pleaded not guilty to the 14 corruption-related charges he's facing, including fraud against the government and breach of trust.

Defence lawyer Pierre Teasdale told Quebec court Judge Louise Provost each of the Crown's four main witnesses admitted to participating in corruption but none were charged after they agreed to testify against Applebaum.

He said the witnesses all had an interest in shifting the blame to Applebaum in order to avoid prosecution for their own alleged crimes.

"Each one had the opportunity to consider and hope that by incriminating Mr. Applebaum, they would save their own skins," Teasdale said.

The Crown alleges Applebaum accepted cash through a former aide in return for favours given to local real-estate developers and engineering firms.

The charges stem from crimes alleged to have occurred in two separate deals between 2007 and 2010 when he was mayor of Montreal's largest borough.

Applebaum, who served as interim Montreal mayor between November 2012 and June 2013, did not testify at his trial, which heard seven days of testimony entirely from witnesses called by the Crown.

The Crown and the defence's final arguments painted contrasting portraits of the witnesses, especially Applebaum's former aide Hugo Tremblay.

During the trial, Tremblay testified having led developers and businessmen to believe their projects would be delayed or not approved unless they made a cash contribution.

He allegedly then split the money with Applebaum, the court heard during the trial.

In her closing arguments last week, Crown prosecutor Nathalie Kleber said Tremblay was new to politics at the time of the events and had testified that it was Applebaum who had taught him how to fundraise both legally and illegally.

Kleber argued the witnesses were credible and their cumulative testimony was enough to prove Applebaum's involvement in the alleged scheme.

But Teasdale countered the Crown didn't provide enough evidence to back up Tremblay's testimony and failed to show any of the money he collected went to Applebaum.

He described the Crown's key witness as an "opportunist" who knew the police were investigating Applebaum and saw a chance to save himself from prosecution by accusing his former boss.

Teasdale also suggested that Tremblay had an "overly familiar" relationship with his police contact that included a large number of calls and text messages, some of them concerning personal matters.

Even though the witnesses hadn't been formally offered immunity, Teasdale said it was "unreasonable" of the Crown to say they hadn't benefited from their co-operation with authorities.

"Not being charged is the best advantage they could have asked for," he said.

Final arguments will continue on Wednesday.