A Timeline of Events in the Gilgo Beach Serial Killings

An architect who had lived most of his life in Nassau County and worked in Manhattan was arrested on Thursday night in connection with the killings of four women near Gilgo Beach on Long Island’s South Shore. The discovery of their bodies and seven others in 2010 and 2011 terrified residents and the case remained unsolved for more than a decade.

Here are the events that led up to the arrest of the architect, Rex Heuermann:

MAY 1, 2010

Shannan Gilbert disappears.

Ms. Gilbert, 24, was an aspiring actress from Jersey City, N.J., who worked as an escort. She was last seen on May 1 after a job in Oak Beach, a gated community several miles from Gilgo Beach.

DEC. 11 to 13, 2010

Four bodies are found along Ocean Parkway.

While searching for Ms. Gilbert’s body, the Suffolk County police discovered four bodies over three days along Ocean Parkway between Gilgo Beach and Cedar Beach, nearby. The bodies were spread over about a quarter mile, each roughly 500 feet apart.

DEC. 14, 2010

Police suggest a serial killer may have been behind the deaths.

Richard Dormer, the commissioner of the Suffolk County Police Department, said at a news conference that it was not “a coincidence that four bodies turned up in the same location,” adding that “it appears as though somebody targeted these individuals and dumped them.”

Mr. Dormer said it looked as if a car had pulled up on the side of the roadway and “dumped them in the bushes.” He said that “the bodies would indicate they were dumped there by the same person or persons.”

DEC. 15, 2010

The four victims are all determined to be women.

Officials investigated whether two of the women could be Ms. Gilbert and Megan Waterman, 22, of Scarborough, Maine, who had advertised herself as an escort on Craigslist and was last seen leaving a hotel several miles northeast of where the bodies were found.

JAN 19, 2011

The first body is identified as Megan Waterman’s.

Ms. Waterman’s death was ruled a homicide.

JAN 24, 2011

The other three women are identified.

The victims were identified as Maureen Brainard-Barnes, 25, of Norwich, Conn.; Melissa Barthelemy, 24, who had been living in the Bronx but was originally from the Buffalo area; and Amber Lynn Costello, 27, who was last seen in North Babylon on Long Island.

Ms. Brainard-Barnes had been missing since July 9, 2007; Ms. Barthelemy disappeared on July 12, 2009; and Ms. Costello was last seen on Sept. 2, 2010.

The police said all of the women whose remains were found were escorts.

APRIL 4, 2011

The police find the remains of a toddler.

While searching for Ms. Gilbert’s body, investigators found the remains of eight women and one man in his late teens or early 20s, who the authorities said was wearing women’s clothing and appeared to have died a violent death.

On April 4, they found the body of a toddler. The little girl’s body had been hidden in a thicket of branches and poison ivy off Ocean Parkway. She was between 18 months and 24 months old at the time of her death.

DEC 13, 2011

After finding a total of 10 bodies, police announce they have discovered Ms. Gilbert’s remains.

Law enforcement officials said they had found the “skeletal remains” of Ms. Gilbert. Officials said they thought Ms. Gilbert had drowned while trying to reach the parkway after knocking on a door in Oak Beach.

NOV. 12, 2016

A docuseries about serial killings airs an episode about the deaths on A&E.

“The Killing Season,” an eight-episode series, was created by the filmmakers Joshua Zeman and Rachel Mills. The series, which also examines deaths in places like New Jersey, Florida and New Mexico, wasn’t the first to delve into the killings: A&E broadcast “The Long Island Serial Killer” in 2011, and in 2016, the network Investigation Discovery began a series, “People Magazine Investigates,” with a two-hour installment on the case. Years later, in 2020, Netflix released a film called “Lost Girls” about the case, which was based on Robert Kolker’s book “Lost Girls: An Unsolved American Mystery.”

JAN. 16, 2020

Officials release the first major clue about the possible killer in nearly a decade.

Investigators showed a photograph of a piece of evidence collected at the beginning of the investigation: a black leather belt, embossed with a pair of letters about half an inch tall that officials believed spelled out the initials “W.H.” or “H.M.” Officials said they thought the belt was handled by the suspect. The police also created a website with information about the case where people could leave tips.

JULY 13, 2023

Rex Heuermann is arrested in Midtown Manhattan.

A bail application prosecutors filed in Suffolk County Court in Riverhead said Mr. Heuermann had been charged with first degree murder in three of the killings: those of Ms. Waterman, Ms. Costello and Ms. Barthelemy. He was named as the prime suspect in the death of Ms. Brainard-Barnes.

Mr. Heuermann pleaded not guilty.