A suspected accomplice in the brutal stabbing death of a retired North Stamford schoolteacher is scheduled to testify against her boyfriend and co-defendant Tuesday.

Jennifer Kos, 35, and Harry Gonzalez are charged with the 2005 murder of 75-year-old Joanne Trautwein. Police say Kos held down the victim's roommate as Gonzalez slashed Trautwein's throat. Rather than face a life sentence, Kos' lawyer says she has agreed to testify against Gonzalez in exchange for a 10-year prison term.

Despite Kos' expected testimony, experts say Gonzalez's case is not over. They say the defense will assert that Kos has too much to gain from speaking against her boyfriend to be taken at her word.