Accused Gilgo Beach serial killer Rex A. Heuermann’s legal team is fighting a request from Suffolk County prosecutors to obtain a cheek swab for DNA testing.

Danielle Coysh, who is representing the triple-murder suspect, argued the Suffolk County District Attorney’s Office is a “far cry” from the legal benchmark that would force the architect to provide the swab, Newsday reported Tuesday, citing court documents.

The back-and-forth between the defense team and prosecutors focused on authorities’ evidence of pizza crusts and a tossed napkin in the garbage that they alleged tied Heuermann to one of the three slayings.

“The assertions contained in the people’s moving papers might be construed as rising to the level of a reasonable suspicion, but that is a far cry from the standard of probable cause required to justify granting the order sought by the people,” Coysh reportedly wrote, arguing prosecutors didn’t have probable cause to show her client was the killer.

Coysh’s reply came after prosecutors made the court aware they wanted a cheek swab from Heuermann for more DNA testing last week, Newsday reported.

Heuermann is accused of killing Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Lynn Costello, 27, whose bodies were found near Gilgo Beach in December 2010. He was arrested on July 13 and remains in jail ahead of a highly anticipated trial.

The remains of the three women were discovered strangled and wrapped in burlap. 

Heuermann was tied to one of the grisly murders through mitochondrial DNA profile from a pizza crust and a used napkin that he threw out near his Midtown Manhattan office, prosecutors have said.

Assistant Suffolk County District Attorney Michelle Haddad asked the court last week to sign off on the cheek swab because the pizza crust and napkins can only be referred to as “purported to be used/touched,” by Heuermann, according to the court docs, according to Newsday.

Haddad noted in court papers if Heuermann’s DNA from the swab doesn’t match the DNA profile from the pizza crusts and napkin, “the defense would be presented with a potential trial defense.”

“Thus, there is a clear indication that material and relevant evidence will be found and is crucial for trial,” she wrote.

Coysh, in her filing this week, insisted authorities “essentially concede” they don’t have evidence to prove Heuermann “actually ever came into contact with the pizza crust or used napkin,” the outlet reported.

“Thus, by the people’s own admission, the nexus between the partially eaten pizza crust and used napkin and the defendant Rex A. Heuermann is at best a matter of conjecture and assumption, not fact.”

The 59-year-old has pleaded not guilty to first-degree and second-degree murders.

He’s also the prime suspect in the slaying of a fourth woman, Maureen Brainard-Barnes, 25, authorities said.

All four victims were sex workers.