Three people are due in a Connecticut court Thursday after police found a teenage girl missing for more than a year — and feared dead — hidden under a staircase.

Adam Gault, his common law wife Ann Murphy and a third woman will face multiple charges at 11 a.m. ET after the police's shocking discovery of 15-year-old Danielle Cramer Wednesday in Gault's unkept West Hartford home.

Other girls may have experienced "something very similar to what's going on right now with this young girl," Police Capt. Lori Coppinger said Thursday, adding that he may have had contact with two or three other girls.

Gault, 41, and the girl frequently talked before she vanished in June 2006, Bloomfield Police Capt. Jeffrey Blatter said.

"There was an inordinate amount of contact via cellular phone and then, during follow ups, there were a lot of other circumstances that led us to believe there was an inappropriate relationship," Blatter said Thursday on a major news network.

Already fearing the worst and with evidence of foul play in hand during Wednesday's investigation, one investigator pushed aside a nondescript dresser by the stairway to reveal a small, hidden door. He slid open the lock and peered inside.

Click here for FOXNews.com's Crime center.

"Lieutenant, you better get in here," he called out, incredulous, as the ghostly pale teen peered up from the bare floor.

Expecting to leave the house with a DNA swab and perhaps other evidence, police instead left with Cramer herself — timid, silent and in tears, but alive.

"The outcome was phenomenal and quite unexpected," Blatter said.

The Bloomfield girl was whisked away for medical and psychological exams, and was in protective custody Wednesday night.

Police described the hidden room as about 3 feet high and 4 feet to 5 feet deep. They were investigating Wednesday whether it was built intentionally to confine the girl, who vanished at age 14, or whether it was simply a convenient hiding place that already existed in the structure.

The Hartford Courant reported Thursday that the police had considered Gault "a person of interest" for months. Gault knows the Cramer family professionally, the paper said, through his dog day-care business.

The teen had no obvious external injuries. Investigators would not speculate on what she might have experienced over the past year.

"We can all assume a 14-year-old under the influence of a 40-year-old had been harmed in some way," Blatter said.

Gault was charged with unlawful restraint, reckless endangerment, custodial interference, interfering with an officer, risk of injury to a minor and forgery.

Murphy, 40, described by police as Gault's common-law wife, was charged with conspiracy to commit reckless endangerment, conspiracy to commit custodial interference and risk of injury to a minor.

Another resident, 26-year-old Kimberly Cray, was charged with reckless endangerment, conspiracy to commit custodial interference, risk of injury to a minor and conspiracy to commit unlawful restraint.

The cases involving the other girls have not been prosecuted because the frightened girls were reluctant to give statements necessary to pursue the cases. Police said they will be interviewed and additional charges may be filed against Gault.

Authorities said the girl had run away from her Bloomfield home several times before vanishing last June.

"She is a child from troubled circumstances and found what she believed to be a friend," Blatter said.

Initially, investigators worried she might have been the victim of a homicide. In fact, Blatter said, they already had collected "bits and pieces of evidence that suggested foul play," all of which were the basis for the search warrants.

Blatter said it did not appear the girl lived in the hidden room, and that police did not find bedding or other items that would suggest it was used as living space.

Police were unsure how long she was there before they found her Wednesday, but that she could not have opened the locked and barricaded door on her own.

Police already had established that Gault knew the girl, and said he and the girl's parents had some sort of undisclosed business transaction in the year before she disappeared. Officers had questioned Gault several times, but he always denied any involvement in her disappearance.

Without a search warrant, investigators never got past Gault's front door — until Wednesday morning.

Other people also had been living in the house, including a 15-year-old boy, though it wasn't clear whose child he was. The boy's case has been referred to the Department of Children and Families, which will also decide if the missing girl should be returned to her parents.

"Unfortunately, this juvenile was in a lifestyle that was not the greatest," Blatter said. "This poor child has been through a lot."

They are investigating whether Gault has been involved in any similar incidents, he said.

By Wednesday afternoon, a large media contingent converged near Gault and Murphy's white two-story home along the West Hartford/Newington line. An empty chain-link dog kennel with two doghouses could be seen in the back yard. A sign on the front door read, "Dogs loose. Do not open front door."

Neighbor Linda Abel Palakewitz said she did not know the couple well and had never seen the girl, whose picture she was shown by a detective Wednesday afternoon.

"To think that they can go and do that and have a child captive," she said. "No one knows what goes on inside closed doors.

“I cried for her. ... You’re only a child once in your life."

The Associated Press contributed to this report.

Click here for FOXNews.com's Crime center.