Here’s the gross reason accused Gilgo Beach serial killer Rex Heuermann has been hobbling on crutches

The hulking Massapequa Park architect skipped out on his Suffolk County court appearance last month because of an undisclosed ailment that had him hobbling around on crutches, according to his defense attorney Michael Brown.

Accused Gilgo Beach serial killer Rex Heuermann has been “stumping along” on crutches due to a grotesque foot problem caused by his heavy weight. Getty Images

Though his attorney declined to elaborate upon the mystery ailment at the time, Heuermann, 62, has been “putting on weight” since he was thrown behind bars — causing him to suffer from gnarly foot problems, sources told The Post.

“He’s a big fat man. It’s a foot issue. It’s an offset [of his weight],” one source said.

“He has a foot problem. It split open and was oozing. He’s still stumping along,” the source added.

The accused serial killer stood at 6-feet-4 inches, and weighed 280 pounds nearly three years ago, NewsNation previously reported. Photos from more recent court appearances show him visibly pudgier than when he was first arrested.

Heuermann pictured in court in January 2026, roughly two-and-a-half years after his arrest. Getty Images

“Rex has been putting on weight in prison,” another source said.

Heuermann is expected to plead guilty to a string of seven sex worker murders in Suffolk County court on Wednesday — and admit to killing a newly revealed eighth victim in a stunning development, according to sources.

Suffolk County District Attorney Ray Tierney has linkedHeuermann to the murders of Valerie Mack, 24, Jessica Taylor, 20, Megan Waterman, 22, Melissa Barthelemy, 24, Maureen Brainard-Barnes, 25, Amber Lynn Costello, 27, and Sandra Costilla, 28.

The string of killings — including four women known as the Gilgo Four — went cold for several decades until investigators finally made a break and arrested Heuermann outside his Manhattan office in July 2023.

Heuermann is expected to plead guilty to a string of seven sex worker murders in Suffolk County court on Wednesday, and admit to killing a newly revealed eighth victim. Suffolk County Police Department

The alleged killer is expected to also admit to the murder of Karen Vergata, a sex worker who had not been previously linked to Heuermann, sources said.

All of the victims peddled sex through online ads in the metro area before vanishing.

The maximum sentence on a second-degree murder conviction in New York State is 25 years to life, with sentences to run consecutively for each individual case, or up to 175 years to life in Heuermann’s case.