Tony Pope entered guilty pleas on Friday to killing his wife, his 13-year-old stepdaughter and 5-week-old infant son.
He received three sentences of life in prison without parole in the appearance before Criminal Court Judge Doug Meyer.
Authorities earlier said Pope had "very calmly" described carrying out the killings of Andrea Pope; her daughter, Brianna Justice; and young son, Christian Pope.
The incident happened in a brick duplex at 1208-B Helena Drive in Hixson in early May 2005.
The state earlier filed notice that it planned to seek the death penalty. District Attorney Bill Cox said his office was approached on Wednesday by defense attorneys, who said Pope had decided to plead guilty.
District Attorney Cox said he and fellow prosecutor Barry Steelman met Thursday with surviving family members and with investigators.
He said it was decided to accept the plea "because it brings the certainty of three first-degree murder convictions and the certainty that he will stay in prison for the rest of his life."
He said even if the state had obtained the death penalty, there is no certainty it would have been carried out.
The defendant was represented by Karla Gothard and Mary Ann Green of the public defender's office along with attorney Rich Heinsman.
Pope had been convicted of second-degree murder in 1995 and served 30 percent of a 15-year term.
Det. James Tate earlier testified that Pope told how he killed his wife by hitting her repeatedly in the head with a hammer, then he strangled the stepdaughter and knocked the life out of the baby after first kissing him and telling him he loved him.
Det. Tate said Pope said he and Andrea had been having marital problems for some time. He said Pope stated that she told him she was going to leave that day and take the children to spend a few days with her mother, then she was planning to divorce him.
He said Pope said he followed her through the house, but she refused to talk to him. He said that when she went out to the laundry room off the carport, he began hitting her in the head with the hammer.
Det. Tate said, "He said he tried to talk to her, but she wouldn't talk."
He said Pope had cut the phone line that went to the duplex.
Det. Tate said Dr. Frank King, the medical examiner, said Ms. Pope was struck in the head 8-10 times with a blunt instrument.
Pope said he left the hammer in the floorboard of his vehicle, and officers found it there. It was displayed at the hearing.
Det. Tate said Pope stated that he went back into the main part of the house and found Brianna screaming at him. He said she went to her bedroom, "slamming the door in my face."
Pope said he pushed his way into her room, grabbed her by the throat and choked her until she collapsed on the floor. He then kicked her in the chest.
Dr. King's report said she suffered strangulation and blunt-force trauma. Her sternum was cracked and eight ribs were cracked - four on each side. She had a bruise on her chest in the shape of a footprint.
Pope said he then went to the crib in the living room where his baby, Christian Pope, was lying. He said he got the baby out "and told him he loved him. He kissed him and said he would be better off in Heaven."
He said Pope stated that he then "lost it and dropped the child, who hit his head on the floor." He picked up the baby, formed his hand into "an eagle claw" and struck the baby two times in the abdomen.
He said he had thought the baby was not going to die, but after he struck him the two blows, the baby "didn't make any more noise."
Det. Tate said Pope then left the residence, and he drove across Chickamauga Dam, then onto Amnicola Highway. He went to an area where there are ducks, and he drove up a dirt road.
He said Pope said he "sat and did a lot of thinking" until morning.
He then called a truck driver named Downey at his work at East Chattanooga Lumber. He also called his boss, Jeff Parker. He said he discussed going to Florida, but the boss "told him he needed to come in and face his actions."
Pope was arrested without incident by two plainclothes fugitive detectives after he did go to the lumber company on Crutchfield Street off Amnicola Highway about 7:30 a.m.
Det. Tate said that during his interview, he told him he thought Andrea Pope was still alive.
James Hostetter said he was the first officer on the scene at the duplex, going out on a call of an "unknown problem" about 10:30 p.m.
He said Chris Burton, brother-in-law of Pope and owner of the duplex, "was very worried. He felt something bad had happened."
He said Chris Burton said, "I think he's killed them." The officer said he asked "Who?", and he replied, "Tony."
Mr. Burton added, "He had killed before."
Officer Hostetter said Mr. Burton had talked to Tony Pope on the phone and was told that he had left Andrea in the laundry room. The officer said he walked to the back of the laundry room, and he said keys given him would not unlock the door. He said he thought he heard someone inside breathing heavily, but it turned out to be a fan.
He said he then took a knife and got the laundry room door open. He said he spotted Andrea Pope sitting on the floor with her back against the wall and blood all over her head and face.
Officer Hostetter said he and other officers then went in the front door carrying flashlights. They found Brianna lying on her back covered up with a quilt in the front bedroom. She had blood on her face.
The dead baby was found in the crib.
Det. Tate said Tammy Miller, a sister of Andrea Pope and of Mary Burton (wife of Chris Burton), had called Chris Burton after talking with the mother. He said the mother had gotten worried because Andrea and the children had not shown up at her residence.
Det. Tate said Chris Burton said he went to the duplex and talked with Tony Pope about 9:15 or 9:30 p.m. He was standing out by the carport. He said they talked about the marital problems and possible solutions.
The detective said Chris Burton said he heard strange noises coming from the laundry room. He said Pope told him it was the freezer, but apparently it was moans coming from Andrea.
The detective said Pope told Chris Burton that Andrea's friend, Elaine, had come by and picked her up.
Pope pleaded guilty in the earlier case to beating his girlfriend to death with a frying pan at a residence in East Ridge.