Ethics and Anti-Corruption Commission detectives on Wednesday arrested former Ugenya MP Chris Karan over alleged forgery.
Mr Karan, a close ally of opposition leader Raila Odinga, has been under surveillance since last year over claims that he forged a letter that was used in an election petition challenging his victory.
Detectives claimed that the letter was forged to allow Mr Karan argue in the case filed by the current MP, David Ochieng', who had challenged his 2017 win.
Mr Karan, who lost to Ochieng' in April's by-election, was arrested alongside one of his lawyers. He will be charged with forgery, a crime that could sabotage his future outing in elections.
After losing by a margin of 4,000 votes, Karan still contested the outcome, claiming that he had been rigged out by Mr Ochieng' of MDG.
“We had taken over Ugenya until the last day when security forces were brought from other counties to come and camp in Ugenya," Mr Karan had claimed.
"The IEBC was equally partisan and in some polling stations, ODM agents were ejected and did not witness the counting of votes,” he said, adding that he was consulting his lawyers and party on whether to take the matter to court.
Mr Karan, however, maintained he was denied victory and defended ODM leader Raila Odinga on claims he kept off the polls hence the loss.
“Jakom (Raila) was in Ugenya three times and he campaigned for me. We were far much ahead. Only the security involvement messed us up,” Mr Karan said.