DA Greg Oakes made the announcement after law-enforcement officials searched the site off of Rice Road in the town of Mexico for four days.
Oakes says that despite the lack of evidence of human remains, the DA's office has not finished its investigation into the matter.
Oakes says his office will now attempt to interview witnesses who may have knowledge of the 20-year-old case.
Oswego County Sheriff's Investigators, as well as Oakes, arrived at the scene of a dismantled cabin on Sunday.
They were joined at certain points by members of Heidi Allen's family, as well as Federal Defense Lawyer Lisa Peebles.
Peebles filed a motion to vacate the 1995 conviction of Gary Thibodeau on an abduction charge.
Peebles believes there may be additional suspects in Allen's disappearance and her remains may have been hidden under a cabin in the woods by three men.
The reports are based on the claims of a woman who came forward last year saying she was friends with one of the men involved.
Oakes refuses to call the three men suspects, saying he has no "credible evidence" leading him to believe that right now.
He noted, however, that the case has never been closed and certain people have recently come forward who he intends to interview.
"My first and foremost concern is always doing justice. If Gary Thibodeau did not commit this offense, then others did and that means that there are people who are capable of this type of crime in this community who are free. If those people exist, I want to find them, I want to prosecute them, and I want to put them in prison," Oakes said.
A private investigator and a reporter from Syracuse.com prompted the investigation at the Mexico site when they found the cabin.
On Monday, a State Police cadaver dog "alerted twice" near a scene being investigated in connection to Allen's disappearance, according to Peebles.
Oakes acknowledged that the dog "alerted," but added that its handler noted that the conditions were less than ideal for an accurate search.
He said the Highway Department brought equipment to the search site on Thursday.
According to Oakes, crews dug a space 20 by 30 feet wide and 4.5 feet deep - and that there was no indication that the ground had been disturbed below the surface or that anything had been buried there.
Reports earlier in the week indicated that footprints were found near the site.
The District Attorney's Office says a local couple admitted they had visited the site after hearing news reports regarding the Allen case. Oakes says there is no reason to believe they are connected to Allen's disappearance.
Earlier in the week, Peebles speculated that someone had gone to the site to remove evidence.
“We believe that somebody went there intentionally to get rid of whatever was there. It’s just our speculation right now, but it’s coincidental that all the media coverage has taken place people start talking about the cabin back there and it’s gone, it’s all torn up,” Peebles said.
Oakes declined to comment on Wednesday's efforts at the site, but he launched sharp criticism at the public defender who filed a motion to free Thibodeau.
Heidi Allen’s sister, Lisa Buske, visited the site on Wednesday.
Buske read a statement indicating that they are still waiting for more information while the authorities search the area.
Buske also said the family appreciates the media’s discretion while the family waits.
Allen was last seen on Easter Sunday in 1994.
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