Detroit -- Jamar Pinkney Sr. calmly admitted during testimony Wednesday that he marched his teenage son naked into a vacant lot in Highland Park and executed him by shooting the kneeling youth in the face.

The 37-year-old U.S. Postal carrier said he lost control and entered an “out-of-body experience” on Nov. 16 when he started beating his 15-year-old son in front of a house-full of relatives because he said the teen admitted having sex with his 3-year-old half-sister.

“I was horrified about the information he gave me about raping my daughter,” Pinkney testified in Wayne County Circuit Court where his murder trial entered its third day Wednesday.

“I told him to strip and walk out the door to the field. He trotted out,” Pinkney said.

“He walked to the field and I walked up behind him and he fell to his knees and I shot him in the head.”

Pinkney is accused of first degree premeditated murder, but his lawyers have said they hope Judge Brian Sullivan will instruct jurors before they begin deliberations today to consider convicting Pinkney of voluntary manslaughter. The difference is mandatory life without parole for murder and a maximum of 15 years for manslaughter.

Pinkney showed little emotion when he took the witness stand Wednesday. Although he began his testimony by answering a simple, “Yes,” to his lawyer Corbett Edge O’Meara’s question about whether he loved his children, Pinkney never said he was sorry.

“I admit to shooting my son, yes,” he said.

When asked by Wayne County Assistant Prosecutor Christine Kowal if he understood he had been the only witness in the three-day trial to say he heard his son admit to having sex instead of only rubbing against the girl, Pinkney said, “I can’t speak for anybody else, why they didn’t tell the truth. That’s what I did. Tell the truth.”

The teen’s family, including his mother, Lazette Cherry, had testified that the boy admitted touching, but not raping, the girl. They told about hours of meetings where the boy was questioned and members of the family debated whether the best course was criminal charges or counseling.

The children have different mothers.

Witnesses said they were shocked when Pinkney erupted into a homicidal rage, beating the teen as the boy pleaded for forgiveness.

Pinkney said at first he didn’t believe a report that his son had inappropriate sexual contact with the girl. The child had “acted out” while watching television with an aunt, he said. When told to stop, Pinkney said he was told the toddler explained, “Jamar did this to me.”