PORTLAND – Steven Clark told his father that he fired the shot that killed his friend and former employee Robert Wagner as the two were arguing after a night of drinking, according to a police affidavit released Friday.

The document filed in District Court shed light on the slaying of Wagner, 28, of Gray, whose body was found in a shallow grave behind the home of Vincent Clark in West Baldwin. Clark’s son Steven, 28, has been charged with murder.

The elder Clark quoted his son as saying the fatal shooting took place early on the morning of Feb. 15 while he and Wagner were in the midst of an argument at Clark’s home in Portland.

“They had a loaded gun and were passing it back and forth. When Steven had the gun, it went off, and a bullet struck Rob in the head. Rob was suffering, so Steven shot him again, killing him,” Vincent Clark told police, according to the affidavit.

Clark, his brother Matthew and their father helped transport Wagner’s body and a blood-stained chair to West Baldwin.

Wagner’s brother reported him missing about 36 hours after he was last seen drinking with Clark at a strip club in Portland. Clark was arrested Feb. 22 in Westbrook, where he apparently had been staying with a friend, and is being held without bail in the Cumberland County Jail.

The affidavit quoted Vincent Clark as saying he learned of the slaying when his two sons arrived at his home on the evening of Feb. 15 and Steven told him that he had killed someone.

The father said Steven told him he could not go to prison or he would kill himself.

Wagner was a former employee of Steven Clark’s mortgage company and later went into the business himself. Clark closed his Sebago Lake Mortgage Co. late last year amid complaints to the state that it failed to arrange promised loans and pay commissions.