A Florida man has died in prison while serving a life sentence for the deadly stabbing of his middle school classmate in 2004.

Michael Hernandez, now 31, was seen on surveillance video collapsing to the floor. Reports said an autopsy would be conducted to determine the cause of death, according to Crime Online.

Hernandez was formally declared dead at a hospital in Lake City near the prison. The Florida Department of Law Enforcement (FDLE) will investigate the incident. There were no signs that he had been attacked.

The Miami-Dade State Attorney's Office has released a statement with regards to Michael Hernandez's death.

"Upon his conviction, Michael Hernandez' family was also scarred by Michael's actions. My sympathies to both families," the office said.

Jaime Gough's parents commented on the death of the Florida man. Maria Gough, the victim's mother, said she does not "feel joy" over Hernandez's death, just sad, CBS Local Miami News reported.

READ NEXT: 9-Year-Old Girl Held Captive, Beaten and Molested by Indiana Man

The Murder in 2004

Michael Hernandez was 14 years old at the time of the crime. He stabbed his middle school classmate Jaime Gough more than 40 times in a bathroom stall at Southwood Middle School in Palmetto Bay before hiding his knife in his backpack and attending a class, NBC Miami reported.

Police were called when people noticed blood on the suspect. Investigators later learned that the Florida man was obsessed with serial killers and had made a list of people he wanted to kill, including then 14-year-old victim, Gough.

Michael Hernandez had planned to kill two classmates in the bathroom the day before, but one refused to go with him to the restroom.

The Florida man reportedly felt he was on a mission to "cleanse the planet" by killing. Hernandez also likes to listen to violent "death metal" music and fascinated with genocidal historical figures such as Adolf Hitler.

Gough's parents earlier said in a letter to a Miami-Dade Circuit Judge that Hernandez is a threat to the community and people would "be living in fear" if he would be released. During the 2008 trial, jurors rejected Hernandez's plea to insanity and convicted him of first-degree murder. 

The trial testimony also showed that the Florida man wanted to kill his own sister. He was particularly fascinated by serial killers such as Ted Bundy and Jeffrey Dahmer.

The suspect's father, Jesus Hernandez, said at the time that the family hoped to get his son better psychiatric help and a sentence that at least allows him for a future chance at parole.

"I think he needs help but prison is not the right place," Jesus Hernandez noted. 

But Hernandez's father admitted that his son even asked him to look up information about serial killers in telephone calls from jail. This was revealed during the questioning by Assistant State Attorney Gail Levine.

Jesus Hernandez also said that he played music clips over the phone for his son from "death metal" bands with lyrics filled with violent, bloody imagery.

The suspect's father said that for him, they were just songs when Levine asked him if it does not worry him that his son is still fascinated by serial killers. 

Footage showed that Michael Hernandez appeared to have died in his jail cell on Thursday.

READ MORE: Texas Teacher Sexually Abused Her Former Student for Years: Police

WATCH: Man Convicted for Killing Middle School Classmate Dies Behind Bars - From WPLG Local 10