Rex Heuermann, the prime suspect in the Gilgo Beach serial murders, has pleaded not guilty to six counts of murder, three counts of first-degree murder and three counts of second-degree murder, connected to the deaths of Melissa Barthelemy, Megan Waterman, and Amber Costello. His arrest came after a meticulous investigation involving DNA analysis, witness testimonies, and persistent police work.

The investigation began between 2010 and 2011 when authorities discovered eleven sets of human remains along a Long Island beach highway. A key piece of evidence, male hair found wrapped in burlap with Waterman's body in 2010, initially yielded limited information due to technology constraints. However, advancements in DNA analysis in 2020 allowed investigators to determine a specific male DNA profile from the hair.

A witness to Costello's disappearance reported a first-generation Chevrolet Avalanche as the potential suspect's vehicle. This crucial detail led investigators to Heuermann, who owned a similar vehicle. Under surveillance, Heuermann was observed discarding a pizza box in Manhattan. Subsequent DNA analysis of the pizza crust revealed a mitochondrial profile matching the hair found with Waterman, statistically excluding nearly all of the North American population.

The bail application further revealed Heuermann's alleged use of fictitious names and online accounts to solicit sexual activity. While Heuermann's DNA could not be definitively excluded from the hair sample, the mitochondrial match combined with the witness testimony and vehicle identification provided compelling evidence for his arrest.

Heuermann, a married father of two and a practicing architect in Manhattan, resided on Long Island. In a 2022 interview, he described himself as an architectural consultant and troubleshooter. Suffolk County Executive Steven Bellone emphasized the long-standing focus on bringing justice to the victims and their families in this complex and tragic case.