John Mann IV of Centereach appears at his sentencing at...

John Mann IV of Centereach appears at his sentencing at the Arthur M. Cromarty Court Complex in Riverhead on Thursday. Credit: Tom Lambui/Tom Lambui

A Centereach man who admitted beating a friend to death with a baseball bat when they were both 16 years old and later burying and then digging up his victim’s remains to move them to a neighbor’s yard was sentenced to 20 years in prison Thursday.

John Mann IV, now 20, apologized for killing Henry Hernandez after he took Mann’s father’s pickup truck and damaged it. He pleaded guilty to manslaughter and tampering with physical evidence in March and will be eligible for parole when he is 36 years old, prosecutors noted during sentencing.

“[Hernandez] took a pickup truck for a joy ride and caused damage,” Assistant District Attorney Frank Schroeder told Acting Suffolk Supreme Court Justice Anthony Senft in Riverhead. “For that crime, this defendant believed that justice required that Henry Hernandez receive the death penalty … [he] decided to be judge, jury and executioner.”

Schroeder said both teens led a troubled existence. Hernandez was born in Guatemala months after his father died. His mother left him to be raised by a grandmother when he was just a month old. He came to the United States with an aunt a decade later.

Hernandez had been in and out of foster homes, had fathered a child and was living on the street by the time he met Mann at a psychiatric hospital in March 2019, Schroeder said. He’d end up spending time with Mann, who had recently attempted suicide, at his home in Centereach until the incident with the pickup truck a month later.

On June 2, 2019, Mann asked Hernandez, who by that point was living at Timothy Hill Children’s Ranch in Riverhead, to meet him at a “sandpit” less than a mile from his house, where he waited for him with duct tape and a baseball bat, he admitted during his change of plea hearing in March. Mann tied the tape around Hernandez’s ankles, wrist and face and struck him repeatedly in the head and body.

Hernandez’s lifeless body was dumped into a previously dug hole and covered with debris, where it remained until March 15, 2020, when Mann returned to dig it up, he admitted. Mann packed Hernandez’s remains first into plastic bags and then a bin, moving them to his next door neighbor’s property on Jay Road, where they were found that day, more than nine months after the murder.

Schroeder said Mann dumped the remains on his neighbor’s property with the hope the neighbor would be blamed.

Suffolk Police homicide detective Mike Repperger pieced the case together over the next two years, Schroeder said. The big break came 11 months into the investigation, when Repperger was able to lift a fingerprint off a piece of duct tape. Police eventually identified Hernandez as the victim and Mann was charged with second-degree murder in June 2022.

 “We hope this plea and sentence serves as some measure of justice for Henry Hernandez and his family,” Suffolk County District Attorney Ray Tierney said in a statement. “This is a truly heartbreaking and horrific case.” 

Mann, who was supported at sentencing by his father and a grandmother, thanked Senft for a sentence that will afford him a second chance at life.

“I will become a functioning member of society,” he assured the judge.

 Senft said the time Mann spends behind bars can be used to improve his life and to think about where he could have ended up had he chosen not to seek revenge on Hernandez. 

“You can write the next chapter in your life,” the judge told Mann.

Defense attorney Matthew Rosenblum, who was assisted by attorney Rudolph Migliore, said he’s confident his client will make the most out of his opportunity.

“It happened. There’s no excuse,” Rosenblum said. “It’s hard to be thankful, and it wasn’t an easy negotiation, but in the end, the system worked here.”

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