A Cranbrook man convicted of murdering his wife and twin babies over 20 years ago is asking for new DNA testing of items of crime scene evidence.

Dean Christopher Roberts has filed a petition in B.C. Supreme Court requesting the release of a cigarette butt, ropes, bags and fingernail clippings.

"The Petitioner intends to make an application for ministerial review on the grounds of miscarriage of justice," reads the petition. "This application requires the petitioner to present fresh, exculpatory evidence."

In July 1994 Susan Roberts and 13-month-old twins Josiah and David were strangled and suffocated to death and their Cranbrook home was set on fire.

Dean Roberts confessed to the crimes during an undercover Mr. Big sting and was sentenced to life in prison with no parole for 25 years in 1995.

The petitions says evidence against Roberts, "was primarily based on his confession during the 'Mr. Big' operation. There was no physical or forensic evidence implicating the Petitioner in the offences."

In 1995 the court heard that Roberts told an undercover RCMP officer that he had previously tried to poison his wife before committing the murders. 

The B.C. Court of Appeal dismissed Roberts' appeal application in 1997.