Twenty-seven-year-old Emilio Rivera, of McKees Rocks, and 19-year-old Marcus Andrejco, of Rankin, allegedly posed as FBI agents when they went looking for money and drugs at the home in Clairton, about 10 miles outside Pittsburgh, on April 4, 2011.
Police say Clairton Officer James Kuzak was shot five times as he arrived in his patrol car.
An Allegheny County jury picked Monday was expected to hear opening statements in the trial Tuesday.
Police arrested Andrejco days later, but didn't charge Rivera until six months later after he was caught on a wiretap planning a similar crime.
Both suspects have claimed alleged confessions to police were coerced.