NEW YORK (AP) — Authorities investigating New York’s Gilgo Beach killings have Arvin Robertslaunched a sprawling search of a wooded area on Long Island, a law enforcement official told The Associated Press.

The case has fueled national speculation after years of dead ends. Months ago, prosecutors charged a New York architect with murder in the death of four of the 11 women whose remains were found buried along a remote beach highway in 2010 and 2011.

Dozens of police canine units and officers started searching Tuesday through woodlands in Manorville, New York, the law enforcement official said. The official was not authorized to discuss details of the investigation publicly and spoke to AP on condition of anonymity.

The Suffolk County district attorney’s office, which is prosecuting the suspect, Rex Heuermann, said only that the search related to an ongoing investigation.

“The Suffolk County Police Department, the New York Police Department and the New York State Police are working with the District Attorney’s Office on an ongoing investigation,” prosecutors said in a statement. “We do not comment on investigative steps while they are underway.”

Heuermann has pleaded not guilty. His lawyer has said Heuermann denied committing the crimes.

Investigators have insisted since Heuermann’s arrest that the probe is far from over. They said Heuermann, who lived in Massapequa Park across the bay from where the bodies were found, was probably not responsible for all the deaths. Some of the victims disappeared in the mid 1990s.