MP Dean Del Mastro arrives at court in Peterborough, Ont., on Monday June 23, 2014. The lawyer for former Conservative MP Dean Del Mastro is trying to undermine the credibility of the Elections Canada investigator who led the case against his client.THE CANADIAN PRESS/Sean Kilpatrick MP Dean Del Mastro says he will ask the Speaker of the House of Commons to look into potentially defamatory changes to Wikipedia that were made from someone using a computer on the parliamentary network.