The Allegheny County trial for 35-year-old Ronald Robinson was to have begun Monday, but was pushed back to January after prosecutors said they couldn't find the witness.
But now that the witness is in custody, jury selection will begin Nov. 12 and testimony on Nov. 26.
Prosecutors allege that Robinson gunned down Penn Hills officer Michael Crawshaw who arrived at the scene shortly after Robinson allegedly killed 40-year-old Danyal Morton over a $500 drug debt in December 2009.
Prosecutors aren't identifying the reluctant witness because they say he has expressed a fear of testifying. He was taken into custody Tuesday night.