A retired Brownsville Police Department sergeant says he can't forget the night of March 11, 2003.

That's the night three children — 3-year-old Julissa, 1-year-old John, and 2-month-old Mary Jane — were killed by their parents inside a home on 8th and Tyler Street.

The parents, John Allen Rubio and Angela Camacho, were convicted in the children's deaths.

Jimmy Manrrique, a retired sergeant with the Brownsville Police Department, was one of the officers who responded to the scene.

Manrrique said an officer was waved down by a family member.

"He just said there was a decapitated baby in the room," Manrrique said.

Manrrique was the sergeant on duty that night.

When he walked into the home, he saw the decapitated body of a child on the bed.

"It's just never seen anything like that. That small of a baby is just something that's just very hard to deal with," Manrrique said.

The parents were already at the police station.

"So we can get them interviewed, and at that point some lady yells that there are three kids," Manrrique said.

The two other children were found inside a black plastic bag. 

Both were decapitated.

Police say Rubio confessed to the murders.

CLICK HERE TO HEAR FROM JOHN ALLEN RUBIO IN AN EXCLUSIVE INTERVIEW

For the officers who responded that night, the emotional toll is something they still carry with them today.

"It's that of the totality of what happened. What the kids went through in their last moments. "As young as they were, as innocent as they were, what they — based on what he told us — what they were thinking when it happened," Manrrique said

Rubio was convicted and sentenced to death in November 2003.

Rubio is scheduled to be executed in November 2026. His attorneys recently filed a motion to declare him to be too incompetent to be executed. 

Camacho is serving life in prison.

Watch the video above for the full story. 

You'll hear more about the investigation, as well as an exclusive interview with Rubio and the investigators involved in this case, in the special report Echoes from Brownsville: The Rubio Murders. It airs on Thursday, May 21.

Click here to watch the trailer.