The unhinged maniac who allegedly killed four homeless people in Chinatown was busted last year for biting a man’s chest during a savage assault, a law enforcement source told the Post.

The 24-year-old suspect, identified by sources as Rodriguez “Randy” Santos, was arrested in November 2018 for an assault in which he leaped over a desk at a store on W. 35th Street in Midtown, grabbed a man by the neck, and bit down on his chest, a high-ranking law enforcement source said.

Santos, also believed to be homeless, has 14 past arrests — four of them in the past year, the source said. He allegedly went on a rampage early Saturday morning, beating five sleeping homeless men on the head with a metal pipe—leaving four dead and one rushed to the hospital in critical condition, police said.

Santos’ last known address is a men’s shelter in Brooklyn, where he was arrested for attacking another man in May — with a metal object similar to Saturday’s weapon, according to sources.

He was also busted last March for groping a 19-year-old woman in Queens, the source said.

Santos remained in police custody after the early-morning spree, and cops said they believe his rampage was “random”.

“Motive appears to be, right now, just random attacks. It doesn’t seem anybody was targeted by race, age, anything of that nature,” Chief of Manhattan South Detective Michael Baldassano told reporters at a press conference.