A Louisiana man decapitated and dismembered his disabled 7-year-old son and left the boy's head on the street so the child's mother would see it, authorities said Monday.

Jeremiah Lee Wright, 30, of Thibodaux, confessed to killing his son, Jori Lirette, shortly after he was brought to the police station Sunday, said Police Chief Scott Silverii.

A volunteer firefighter found the child's head alongside a street Sunday and called the police. Investigators found a white garbage bag nearby with the child's dismembered body inside.

Wright told investigators that he killed the boy after the child's mother, Jesslyn Lirette, left on Sunday to have her truck repaired so she could take Jori to the doctor Tuesday.

Police say Wright decapitated Jori and dismembered his body over the home's kitchen sink, which was sent to the Louisiana State Police crime lab along with a box of tools found nearby.

Jori Lirette was a second-grader at South Thibodaux Elementary School. He had cerebral palsy and heart problems and struggled with his speech. The boy was completely defenseless as he was confined to a wheelchair.

Silverii said the motive was unclear though Wright told police that he was "tired of taking care of the boy."

"During the interview Wright said he was taking care of (the child) for so many years and he just started to look at him as no longer his son, just an inanimate object. He and the child's mother had some issues," Silverii said, reports CNN.

Wright's explanation for the crime was that he wanted Jori's mother to "feel stupid" when she saw her son's head, Silverii added.

Wright has been charged with first-degree murder and is being held on a $5 million bond, said Thibodaux police spokesman Detective Ricky Ross. Wright also waived his right to an attorney, Ross added.

Jesslyn Lirette was devastated at her son's gruesome death.

"He was a very important person in my life. Maybe the best thing that ever happened to me," she said at a news conference.

"He has touched so many people in this community -- in school, my friends and my family ... we all love Jori very, very much. He was a very friendly child, not shy of strangers, he was happy in life. He will be missed sadly and deeply by all his friends and all my friends," she added.

The brutal murder shocked the people of Thibodaux and even unnerved "seasoned" police officers.

"These are experienced men. They came out of there in tears. Just absolutely in tears," said Silverii.

It is the first murder in Thibodaux since 2008.

Wright has no record of violent crime. He was arrested in 2007 on a marijuana charge and for theft on another occasion, Ross said.

"He (Jori) was my star. No matter what people think or say, he was always top priority in my life," Jesslyn Lirette said through tears during the news conference.