(NewsNation) — Suffolk County officials revealed to NewsNation that investigators have obtained 15 reports from sex workers currently behind bars who may have spoken with alleged Gilgo Beach serial killer Rex Heuermann.

Retired NYPD Sgt. Joseph Giacalone told NewsNation’s Laura Ingle he believes the case is going to start “catching fire” in the next couple of months.

“I think this task force has done a tremendous job. And I see some more cases getting solved in the future,” Giacalone added during his Wednesday appearance on “Elizabeth Vargas Reports.“

Heuermann, the man who is accused of killing six women, has pleaded not guilty to all charges against him. Since 2010, police have been probing the deaths of at least 10 people, most of whom are sex workers, whose remains were discovered along an isolated highway not far from Gilgo Beach.

Victims had gone missing over a span of at least 14 years.

Heuermann, an architect who lived across a bay from where the bodies were found, was arrested last July in connection to the killings of Megan Waterman, Melissa Barthelemy, Amber Lynn Costello and Maureen Brainard-Barnes.

At a hearing in June, Heuermann pleaded not guilty to killing Jessica Taylor and Sandra Costilla and was ordered held without bail. Michael Brown, Heuermann’s attorney, told reporters afterward that Heuermann is “horrified by the new charges,” and “obviously in a bad place” regarding them.

He is scheduled to return to court July 30.

NewsNation’s Laura Ingle contributed to this report.