Police charged a father with murder Sunday, accusing him of beating his 6-year-old to death because the boy would not fall asleep.

Police say the fatal, eight-hour beating was the final episode in at least two weeks of abuse that Tekerrious Jackson suffered since coming to spend the summer with his father, 34-year-old Alex McGowen Duncan.

Alex Duncan

“This has got to be one of the most horrifying and heartbreaking cases I’ve ever seen,’’ Houston Police Department Homicide Division detective Sgt. Brian Harris said. “The saddest thing is, that because of the unconditional love he had for his father, the child would often tell him, ‘I love you daddy.’”

Duncan would force Tekerrious — who was called TK — to get on his knees and raise his arms above his head when the child didn’t go to sleep, police said. Harris said Duncan would then proceed to repeatedly punch the child in the chest.

“If (Duncan) didn’t see him with his eyes closed or saw him wink, he would beat him,” Harris said.

Saturday night started the same way, police say. Duncan put TK to bed around 7 p.m. on one of the two mattresses in the small efficiency apartment in the 4900 block of Polk. Duncan shared the one-room unit with his girlfriend, 30-year-old Tammyra Sampson, and her 11-year-old daughter, Harris said.

After Duncan saw TK’s eyes flutter, he forced the boy onto his knees and ordered him to raise his arms above his head and clasp his hands together, Harris said.

Every time TK became tired and lowered his arms or gave an unsatisfactory answer to a question his father asked, he would get what Duncan described to investigators as “chest boxing,” a flurry of punches to the chest and the rest of the body, Harris said.

Daughter was witness

Tammyra Sampson

Harris said the beating continued until 3 a.m. with Sampson and her daughter witnessing the entire event. Harris said Sampson only intervened once to “show” him how to properly discipline a child with a belt.

“She said ‘I stopped him and said ‘If you’re gonna whoop him, let me show you the proper way to whoop him,’’’ he said.

At one point, TK soiled himself, Harris said.

“That sent the father into even more of a rage,” he said.

Shortly afterward, TK began to have what appeared to be a seizure. An ambulance was called and the boy was taken to Texas Children’s Hospital, where he was pronounced dead upon arrival.

Initially, Duncan, who has a history of drug charges dating to 1995, told police that the bruising was from attempting to revive the child from the seizure by slapping him and giving him chest thrusts.

His story, however, did not match the 11-year-old child’s graphic demonstration to police of the beating or Sampson’s statements.

During his interview, Duncan told investigators that he beat the boy in order to show his son how to “man up.”

“He said he was trying to teach him discipline, so he would make good choices,” Harris said, adding that Duncan would also hit Sampson’s daughter, but not as severely because she was a girl.

Duncan is scheduled to appear in court Tuesday. Sampson, who has a criminal history and history with Child Protective Services, has also been charged with injury to a child causing serious bodily injury by omission. Both are in Harris County Jail with a bond of $50,000 each.

With father for summer

Duncan had gone about three years without seeing his son before calling the boy’s mother to say he wanted to be a part of the boy’s life again, Harris said.

The child’s mother agreed to let him stay with his father for the summer. When she left TK in late May, Duncan was living with his mother in the 5300 block of Coke. TK’s mother had not been able to get in contact with them and had no idea they had moved to the residence on Polk with Sampson but was assured that her son was OK by Duncan’s mother.

Neighbors in the small apartment complex were shocked by the news of the child’s death. They said the couple had moved in only a few weeks ago.

“There are people who pay lots of money to have kids. They take medicine so they can have kids and pay money to have other people’s kids,” said one neighbor, who wished to remain anonymous. “How can someone take the life of their own child?”

CPS is investigating and has placed the 11-year-old child with her paternal grandmother.