AURORA, Colo. -- The death penalty murder trial of Sir Mario Owens is moving much faster than expected and jurors were told on Friday that they should expect deliberations to begin next week.

That is much sooner than originally planned. Jurors had been told to expect the trial to last 10 weeks.

Owens is charged with killing Javad Marshall-Fields and his fiancee, Vivian Wolfe, to keep Marshall-Fields from testifying in the murder trial of his friend, Gregory Vann.

Owens is already serving a life sentence for the murder of Gregory Vann at Lowry Park in Aurora on July 4, 2004.

Owen's attorneys began their defense Friday morning, focusing on DNA evidence found at the crime scene. An expert said that even though Owens' DNA was found on a baseball cap, that doesn't mean Owens was there that night.

The defense also said that the key witnesses against Owens all have criminal records and shaped their stories to please prosecutors who, in exchange, gave them plea bargains.

Legal analyst Craig Silverman told 7NEWS that it is not uncommon for witnesses in murder trials to have criminal histories. He said prosecutors have to weigh the greater good in determining when to give plea bargains.

He believes jurors do a good job at sorting through facts and figuring out who is telling the truth.