Amber Lynn Costello: How Did She Die? Who Killed Her?

In September 2010, Amber Lynn Costello left her home to visit a client, after which she went missing. Her remains were soon discovered with the remains of three other women, which sent a shockwave of panic across the community. Her tragic murder became a part of the Gilgo Beach Serial Killings. The breakthrough in the case finally came years later, with a new task force being set up and the advancements in digital evidence analysis. Netflix’s documentary ‘Gone Girls: The Long Island Serial Killer’ focuses on the extensive investigation that finally led the official to the alleged killer.

Amber Lynn Costello’s Remains Were Found By Accident

Amber Lynn Costello was born on February 10, 1983, and brought immeasurable joy to the lives of her parents, Alfred P. Overstreet, Jr., and Margaret Anne Sasse. She was raised in Wilmington, North Carolina, surrounded by the love and support of her parents and her sister, Kimberly Overstreet. Growing up, Amber had always been kind and had a “giving” nature, irrespective of her struggles. If someone were in dire need of help, she would reach out her hand to pull them out of their darkest times. In many cases, her own life experiences motivated her to show empathy for others. At one point in her life, she was hopeful that she had found true love. However, fate had its own twist, and she ended up getting divorced in all two of her marriages.

However, Amber’s struggles did not stop there since she was also battling with drug addiction. In an attempt to take the reign of her life, she became a woman of faith and was quite involved with the church. Determined to help her sister, Kimberly brought Amber to New York sometime in 2009 and got her into rehab. Amber was living in a sober house before she finally moved to her own apartment in West Babylon, New York. However, the grip of addiction held onto her tightly, and she relapsed. In order to support her habit, she became an escort, which eventually became the reason for her untimely demise. On September 2, 2010, 27-year-old Amber received a deal from a client that was higher than she usually received. So, Amber stepped out of her apartment in Babylon and allegedly said to her male friend, Dave Schaller, that she would return soon.

This was the last time Amber was seen, and she had left her home without her cell phone. When she did not return, Dave grew worried and called her sister to ask if she knew about her whereabouts. Kimberly, who was back in North Carolina, allegedly assumed that Amber was in a rehab program. She had thought that this was why no one could contact her. It was not until December 13, 2010, that her remains were discovered in a burlap sack along Ocean Parkway near Gilgo Beach. This revelation was prompted by the accidental discovery of a victim’s remains in the area. In January 2011, a DNA match ultimately determined that the remains were of Amber, and the autopsy results revealed that she had died due to strangulation. The officials had found the remains of three more victims in that area and launched an investigation, which would take them years to find the accused.

The Suspect Had Picked Amber up on the Night She Was Last Seen

When the investigation first started, the police found strands of hair at the scene of the crime. Since all four remains, along with Amber’s, were found in the same place with the same cause of death, they reportedly presumed that this was done by a single individual. However, they did not have any suspect to compare the DNA to. They questioned Dave since he was the last person to see Amber leave the apartment. He alleged that her client had called three to four times that evening. The last call came around 10:30 pm, after which Amber went out. Dave reportedly described this client as “an ogre,” who was 6′ 4″ or 6′ 6,” and had bushy hair. Dave also mentioned that this man was driving a “first-generation dark-colored Chevy Avalanche.”

Despite this witness account, the officials were unable to solve the case since there were no potential suspects in sight. However, the story turned around when the new commissioner, Rodney Harrison, took charge in 2022. Rodney formed a task force, and they started digitalizing 12 years’ worth of evidence to make it easier to search. They started looking at the clues and interviews the officials might have missed previously. The task force soon came across Dave Schaller’s witness account, which was taken shortly after the investigation of her death had started. They reportedly deduced that the type of car that he had explained was used by someone of a large size. They also knew that the alleged killer had used burner phones, which were activated mainly in or around Massapequa Park and Midtown Manhattan. Amber and the other victims had all worked in this area.

The Alleged Killer Has Been Charged With Several Other Murders

Finally, on March 14, 2022, the police identified the suspect, Rex Heuermann, an architect working in Midtown, New York. Upon monitoring his movements, the authorities determined that Rex resided in Massapequa Park with his wife and two children. The police started looking into his phone records and discovered that the burner phones used to contact the victims matched Rex’s location. Upon further investigation, they also found out about his multiple anonymous email accounts, which he used to reach out to escorts. After much trying, they obtained his DNA sample and compared it with the hair samples found on the scene.

This sealed the deal for the officials, and after 13 years, in July 2023, they finally arrested and charged Rex for the murders of Amber Lynn Costello, Megan Waterman, and Melissa Barthelemy. The investigation continued, and he was also charged with the murder of Maureen-Brainard Barnes in January 2024. This was followed by the murder charges of Sandra Costilla (1993) and Jesicca Taylor (2003) in July and Valerie Mack in December. As of writing, Rex has pleaded not guilty to all seven murder charges, and the investigation is still ongoing.