EL CAJON, Calif. -- Gasoline ignited by some sort of open flame started a fire that killed a young man and destroyed an upscale Mount Woodson home, a sheriff's bomb-arson unit investigator testified Wednesday at a hearing to determine if a Ramona filling station owner should stand trial for murder.

James Anthony Kurtenbach is charged with second-degree murder in the Oct. 31 death of one of his employees. The body of 24-year-old Joseph Nesheiwat was found just outside the 4,000-square-foot rental home owned by Kurtenbach.

Prosecutors contend the victim set the fire at the defendant's request, but died when gasoline vapors exploded.

Kurtenbach is also charged with arson causing great bodily injury, arson for financial gain and a number of violations of the state insurance code.

Sheriff's Detective Robert Williamson testified that the day after the fire, he began inspecting the remains of the structure as workers cleared the ruins layer-by-layer.

"When debris was moved around, I smelled what I believed was gasoline," Williamson said.

The detective said the smell got stronger the deeper they got into the pile. He said he also found two distinct "pour patterns" -- marks left by gasoline after it has been tossed about and burned off.

The fire grew too big too fast to be caused by an electrical accident or malfunction of the home's propane system, Williamson said. A private investigator working for an insurance company came to the same conclusion, he testified.

At the conclusion of the preliminary hearing, which is expected to last into Monday, Judge Louis Hanoian will decide whether there is enough evidence to order a trial for Kurtenbach.

Williamson testified that witnesses reported hearing a loud explosion, followed by animalistic screams, and then saw either flames or a large orange glow.

Dr. Glenn Wagner, the chief medical examiner of San Diego County, testified that Nesheiwat suffered second- and third-degree burns over 85 percent of his body.

"He had (soot) all the way down his airway to his lungs," Wagner said. "He also had some in his esophagus and stomach, meaning that he was alive when the fire started and was alive long enough to take several breaths."

The defendant, who lives in Poway with his second wife and is free on bond, owned the Stars Petroleum gas station for seven years.

According to county records, Kurtenbach owed $16,600 in back taxes on the destroyed home at the time of the fire.

The prosecution alleges Nesheiwat had turned down previous requests from Kurtenbach to burn down the home, but he owed his boss money.

The defendant's 25-year-old son, testifying under a grant of immunity, said Nesheiwat was a good enough friend to be in his wedding.

Justin Kurtenbach said his father twice made comments about the Mount Woodson home burning down and that Nesheiwat was there to hear it.

The son said he argued with his father about the comment and told him it was "nonsense."

Terri Kurtenbach, who was married for 24 years to the defendant before they divorced in 2005, testified that after the home burned down, her son told her about the comment her ex-husband had made.

Justin Kurtenbach told her his father said the comment about the house burning down was a joke, the defendant's ex-wife testified.

She said that after her former spouse was arrested, she went to work at his gas station and discovered he was in serious financial trouble, which she had to work with creditors to clear up.