'CSI' Star Wallace Langham Get A Clue I'm Filing For Divorce

9/20/2013 9:50 AM PDT

"CSI" actor Wallace Langham has all the evidence anyone needs ... that his 11-year marriage is DOA ... TMZ has learned.

Langham -- who plays lab technician David Hodges on the show -- has filed for divorce from his wife, Karey Ann Richard... and it's the usual MO ... irreconcilable differences. They've been separated for the last year and a half.

There's one kid  -- a 7-year-old daughter.  Langham's asking for joint custody ... plus, he's asking the court to not award his wife any spousal support.

Case closed.