Elihue Gillespie is the third person involved in the 2009 murder to cut a deal with prosecutors; the fourth is expected to go to trial in June.
As part of the plea deal, Gillespie has to testify against the accused shooter, 24-year-old James Coven.
Court documents say Coven and two friends, Tabitha Burton, 18, and Christopher Gonzales, 26, were getting high one night and decided they needed more drugs.
Gillespie drove the group to Russian Jack Dr. in East Anchorage for the drug deal.
Police say during the exchange, Coven opened fire on the dealers, leaving the two men dead inside their pickup truck.
The victims were identified as Christon Lee and Matthew Peterson, both 19.
Gillespie turned himself and his friends into police and agreed to wear a wire to see if Coven would incriminated himself -- not much came from those conversations.
"There's a sentencing cap of 28 years to serve, so anywhere between the 10 and 28 years should be imposed," defense attorney Andrew Lambert said.
Lambert says Gillespie's cooperation should be a major factor in determining a sentence.
Sentencing is scheduled for August.
