Lorraine Ela, left, mother of Megan Waterman, Mary Gilbert, center, mother of Shannan Gilbert, and Melissa Cann, sister of Maureen Brainard-Barnes. (AP)

Five months after she was found dead in an Oak Beach marsh, investigators still do not know how Shannan Gilbert died, Suffolk County police and an attorney for the family of the New Jersey woman said Tuesday, which marked the second anniversary of her disappearance.

Attorney John Ray and Gilbert’s family met with officials from the Suffolk County Medical Examiner’s office Tuesday afternoon, hoping to get some answers regarding the 24-year-old’s cause of death and the results of her autopsy. But they were given no new information.

“The Suffolk County Medical Examiner’s Office has classified the death of Shannan Gilbert as ‘Undetermined,’” the police said in a statement Tuesday evening. “The Homicide Squad continues to actively investigate the circumstances surrounding Ms. Gilbert’s death.”

Investigators have said they don’t believe Gilbert’s death is related to the victims of a suspected serial killer whose remains were found several miles away along Ocean Parkway. Police were searching for Gilbert when they discovered the other bodies.

Police theorized when Gilbert’s remains were finally found in December that she accidentally drowned while in a panic, after running into the marsh and getting stuck in the quicksand-like area, following an argument with client who had hired her as an escort.

Shannan Gilbert

At the time of her disappearance, Gilbert, unfamiliar with the area, was running alongside the tall reeds that line Anchor Way. In the darkness, she would not have been able to see that those reeds were hiding flooded marsh that, at times, can be filled waist-deep with water.

But Gilbert’s family, and the families of those believed to be victims of a serial killer, say Shannan was running away from someone in the darkness and her death could not have been merely an unfortunate mishap.

“How did Shannan get in that brush with only a shirt and bra on?” said Ela after investigators announced they believed Gilbert’s death was an accident. “Who took her pants off and left her in Oak Beach? She was murdered. She did not accidentally drown. Someone took her out of there and put her on the side of the road.”

Searchers were looking for Gilbert when they found the body of 24-year-old Melissa Barthelemy, the first of the 10 sets of remains discovered on the barrier beach between December 2010 and April 2011. Gilbert had remained missing for more than a year and a half.

A: Joseph Brewer's home, where Shannan Gilbert ran from; B: Anchor Way, where she was last seen running; To the right is the marshland. Blue box: where Gilbert's jeans, cell phone, pocketbook, shoes and lip gloss were found. Red box: Where Gilbert's remains were found. (Google Maps/Long Island Press)

Those with information can call Homicide Squad detectives at 631-852-6396, call Crime Stoppers anonymously at 1-800-220-8477, text tips anonymously by texting “SCPD” to “CRIMES” (274637) or email information via www.tipsubmit.com

There is a $25,000 reward for information leading to an arrest in the case, the highest sum ever offered in Suffolk County history.