SAN DIEGO – Nathaniel Gann and his sister calculated the murder of their stepfather down to the last detail, from buying black clothing to faking a home-invasion robbery and calling 911 for help, prosecutors told jurors during closing arguments Tuesday.

Jurors began deliberations Tuesday afternoon and must decide whether Gann, 20, is guilty of murder and a special allegation of lying in wait.

Gann is accused of firing four shots at his stepfather, attorney Timothy MacNeil, including a fatal shot to the back of the head on July 19, 2007.

“That was no accident. It was not spontaneous, not rash,” Deputy District Attorney George Bennett said in San Diego Superior Court.

During closing arguments, Bennett told the jury that Gann's DNA was found on a ski mask found in a nearby tree, and that neighbors saw a man matching Gann's description running from the house after the shooting. Gann is accused of running up some stairs to his pickup truck and then driving back to his grandmother's house in Arizona, where he was arrested several hours later.

The prosecution also pointed to the testimony of Charles Goodman, a man who shared a jail cell with Gann in Arizona. Gann reportedly confessed his role in the slaying to Goodman before being extradited to San Diego.

“What he told Mr. Goodman matched up with the evidence,” Bennett said. “He has no way of knowing unless it was related to him by the person who killed Timothy MacNeil.”

But Gann's defense attorney, Ricardo Garcia, warned the jury about believing anything Goodman said, calling the convicted felon a liar and mentally ill.

Garcia, of the Alternate Public Defender's Office, also questioned the physical evidence in the case, and on several occasions accused investigators of sloppy police work.

He said there was no gunshot residue found on Gann's hands, no fingerprints found on the gun and nothing in Gann's pickup or home linking him to the crime.

“Nathaniel Gann didn't kill Timothy MacNeil. The evidence does not prove it,” Garcia said. “It's not part of his character or his nature, and that alone is enough. He had no motive; he had no reason to do it.”

Garcia instead argued that Gann's sister, Brae Hansen, was the mastermind and sole suspect behind the crime. Hansen, who is accused of pretending to be the victim during the fake robbery, is set go to trial in January.

Police responding to Hansen's 911 call arrived to the home to find her hands zip-tied behind her back and MacNeil dead on the floor.

She gave detectives several statements that police said didn't add up. She was arrested later that day.

Gann's defense attorney has said Gann and his sister are the victims of emotional and physical abuse at the hands of their mother, who committed suicide in 2005. Police have said the pair planned the killing to gain inheritance money.

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