On Friday, the search extended to North Sea, where Sandra Costilla, 28, was discovered dead in Nov. 1993.
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John Bittrolff has been long suspected but never charged in her death, according to our sister station WABC. Bittrolff was convicted in 2017 in the murders of two other women, whose bodies were found in 1993 and 1994 in East Patchogue and Shirley.
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The search began Tuesday in Long Island's Manorville were both near where Bittrolff used to live and near where the remains of two women in the Gilgo Beach pattern.
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The remains of Jessica Taylor, a 20-year-old sex worker, were found several miles east of the "Gilgo Four" in March 2011. Other remains from Taylor were previously discovered in Manorville, in eastern Long Island, in July 2003.
The remains of Valerie Mack, a 24-year-old escort, were found in April 2011 about a mile and a half east of Taylor's remains and a little over 2 miles east of the "Gilgo Four." Mack's partial remains were previously discovered in Manorville in September 2000, and police have suggested there may be a connection to Taylor's remains.
It is unclear why prosecutors are searching locations linked to Bittrolff, whether he is being looked at for anything else or if they have discovered anything over the past five days.
Many theories were floated about possible suspects in the decade of Gilgo investigations until Rex Heuermann was charged with four of the deaths.
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However, Heuermann has not been publicly linked to at least six other deaths in the larger Gilgo probe and none of his alleged victims were located in Manorville.
ALSO SEE: Accused Gilgo Beach murderer Rex Heuermann appears in court as prosecutors turn over discovery
The Suffolk County District Attorney, whose office is leading the investigation, said he "will not comment on investigative steps while they are underway" and "will make further statements when appropriate."
No one has ever been charged in the deaths of Taylor or Mack.