A struggle between a marine and prostitute armed with a knife in a Waikiki hotel room ended with the prostitute dead on the floor, said a defense attorney for Master Sgt. Nathaniel Cosby during opening arguments in Cosby’s court martial at Marine Corps Base Hawaii in Kaneohe Bay.

Cosby, 39, is charged with unpremeditated murder, murder while engaging in an inherently dangerous act, obstructing justice, and attempting the patronize a prostitute. If convicted of the most serious charges, the marine faces a sentence of life without parole. The charges are in connection with the death of 29-year-old Ivanice "Ivy" Harris, whose body was found on May 20, 2013, in kiawe brush near Yokohama Bay on the Waianae Coast.

In Monday’s opening arguments, defense attorney Lt. Col. Clay A. Plummer said, "It’s "not going to be about who, it’s going to be about why." He added, "What it’s going to come down to is self-defense."

Plummer said that during the early hours on May 16, 2013, Cosby, who had been drinking for 10 hours, was in his hotel room with Harris. At some point, when Cosby was asleep on a bed, the defense counsel said, "She woke him up saying, ‘You need to pay me.’"

Cosby then told her to get out of the room, Plummer said, adding that an argument ensued during which Harris produced a lipstick-like knife with a razor-type blade on it.

"She cuts him right here, slashes across his arm," Plummer said, as Cosby was ushering her to the door. "When that knife slid across his arm, he reacted," Plummer said. Harris then stabbed Cosby in the temple with the knife, the defense counsel said.

"This was a struggle from moment one," Plummer said. While Cosby was going after knife, trying to restrain Harris, they ended up on floor and at some point, when she was no longer moving, the marine knew she was dead, Plummer said. Cosby then made a decision that he needed to get her out of the room, Plummer said.

At sometime after 6 a.m. May 16, the morning that Harris is believed to have been killed, a cellphone tower picked up a signal from Cosby’s recently purchased pay-as-you go phone on the Waianae Coast.

Harris was originally from Oregon. She was visiting Hawaii to celebrate her 29th birthday with her boyfriend, who was also her pimp, and two other women.

Harris’ disappearance started out as a missing person case, after one of the women who traveled to Hawaii with her reported her missing.

Cosby is an explosive ordnance disposal technician with Marine Wing Support Squadron-171 in the 1st Marine Aircraft Wing based in Iwakuni, Japan. He was on temporary duty assignment in Hawaii last May.