An Upper Marlboro man whom police have called a serial killer is going on trial for the March 2009 murders of a Prince George's County mother and daughter.

Opening arguments are scheduled for Tuesday in Jason Scott's trial for the slayings of 42-year-old Delores Dewitt and her 20-year-old daughter, Ebony. The pair's charred bodies were found in a burning car in Largo.

Scott was indicted in 2010 on two counts of first-degree murder, two counts of first-degree burglary and three firearms charges in connection with the Dewitt case.

Harry Trainor, a lawyer for Scott, said his client has pleaded not guilty and that the "defense to these charges will be made in open court during the trial."

Authorities said Scott is also a suspect in the murders of three other people, although no arrests have been made in those cases.

Two of the other people that Scott may have killed are also a mother and daughter: 45-year-old Karen Lofton and her 16-year-old daughter, Karissa. They were found shot to death in their Largo home about two months before the Dewitts were killed.

Additionally, Scott is a suspect in the slaying of 47-year-old Vilma Butler, who was shot in 2008 before her Bowie home was set on fire, police said.

In January 2012, Scott was sentenced to 100 years in prison for federal crimes relating to a series of crimes committed during burglaries and home invasions. Scott was convicted of federal carjacking, child pornography and firearms charges. He has filed an appeal that is still pending, a U.S. Attorney's Office spokeswoman said.

During the murder trial, lawyers will not bring up that Scott was convicted in federal court. But Prince George's County State's Attorney's Office spokesman John Erzen noted that "some of the charges he has here are similar to the ones he was convicted of at the federal level."

Scott's trial in the Dewitt case will be held in Prince George's County Circuit Court, and a jury was selected last week. The trial is expected to last four to six weeks because "there is a lengthy witness list," Erzen said. He noted that prosecutors plan to call up to 65 witnesses.