A second man had been partying with missing Craigslist sex worker Shannon Gilbert the night she disappeared from a Long Island beach community where a serial killer is suspected to have buried his victims, The Post has learned.

The man, a 48-year-old drifter with a penchant for strippers, was staying at the Oak Beach summer home owned by businessman Joseph Brewer, the john who hired Gilbert in May 2010 and was also with her that night.

At one point during their get-together, Gilbert fled in a panic from Brewer's home — just a few miles from where the bodies of four other hookers were unearthed in December — telling one resident: "They're trying to kill me!"

She then disappeared into the night before cops arrived.

Brewer has repeatedly denied any involvement, saying only his "prayers are with the families" of the dead women. Police have said he is not a suspect.

Cops would not say if they have questioned the second man.

His mom told The Post yesterday that her son had contacted her after Gilbert's disappearance. She said she believes he is now somewhere in Georgia.

"He called me," she said. "He told me not to worry if his name was in the papers related to the case."

Police uncovered the remains of four young women on a Suffolk beach while they were searching for Gilbert in December. All were in their 20s and worked as prostitutes.

The remains of four others have now been found within a few miles of there, fueling further speculation that a Long Island Ripper has been using the isolated beach communities for a burial ground. Gilbert has yet to be found.

selim.algar@nypost.com