A man convicted of killing his former girlfriend's three children by letting them drown as their car rolled into a lake was sentenced Wednesday to life in prison.

A judge issued the sentence immediately after the jury decided to find Maurice LaGrone Jr. ineligible for the death sentence sought by prosecutors. Two jurors later said prosecutors failed to prove that LaGrone had intended the children to die.

Six-year-old Christopher Hamm, 3-year-old Austin Brown and 23-month-old Kyleigh Hamm died in less than 5 feet of water at Clinton Lake on Sept. 2, 2003.

Prosecutors had argued that LaGrone, 30, and the children's mother planned the deaths. Defense attorneys said LaGrone made bad decisions, such as parking too close to the water on a boat ramp, but did not intentionally drown the children.

Prosecutor Roger Simpson called the life sentence "acceptable."

"When the guilty verdict came back last night, that was paramount," Simpson said.

Defense attorney Jeff Justice promised an appeal, saying Judge Stephen H. Peters should have given jurors the option of finding LaGrone guilty of involuntary manslaughter.

"This jury was left with no choice," Justice said.

Juror Greg Haddock said jurors did not believe LaGrone meant to kill the children but decided he had put the youngsters in harm's way.

"They were put in a situation that pretty much got out of hand, and he didn't do anything to stop it," Haddock said.

He and fellow juror Louis Villafuerte said LaGrone's testimony worked against him. LaGrone cried when two of his relatives testified, but "I didn't notice any emotion when he talked about the three children," Villafuerte said.

The children's mother, Amanda Hamm, 30, faces identical charges at a later trial. No date has been set.