Played by John Thaddeus

Boston Police Detective John Stephenson first appeared when Catherine Piper approached him in 2x02 [Schadenfreude] with her concerns over the murderous tendencies of Bernard Ferrion. When he dismissed her fears, Catherine took matters into her own hands, killing Mr. Ferrion. Detective Stephenson returned to question her about Mr. Ferrion's whereabouts in 2x03 [Finding Nimmo] and later testified against Catherine in her murder trial in 2x04 [A Whiff And A Prayer]. After testifying for the prosecution, Detective Stephenson was cross-examined by Alan Shore, who ridiculed him mercilessly for his police work, thanking him sarcastically for his "fine commitment to detail" and for conducting a "Sherlock Holmesian investigation". In the end, Catherine was found not guilty.

Detective John Stephenson returns to investigative duty in episodes 3x08 [Lincoln] and 3x09 [On The Ledge].

John Thaddeus
New Jersey native John Thaddeus got his start in television on soap operas, featuring in several different daytime dramas in the mid-1980s. After moving to Los Angeles, he got his first guest role on David E. Kelley's Ally McBeal (1998). He went on to have have many guest roles in Kelley's The Practice and Boston Public, and his other recurring roles include multiple episodes on American Dreams, The Guardian, and 24.

According to Internet Movie Database, he also did soundwork on Ally McBeal and several other Kelley shows, including Boston Legal. He specialized in ADR technology, which is short for either "additional dialogue recording" or "automated dialogue replacement" and refers to a method of dubbing.

John Thaddeus at the Internet Movie Database.