Two years after she went missing, a 6-year-old girl has been found alive and in good health in a makeshift room underneath a staircase in a house in New York state, according to police who said they suspected she was abducted by her biological non-custodial parents.

Officers found the girl, Paislee Shultis, on Monday in a house in the town of Saugerties, two years after she went missing from Spencer, New York, about 180 miles (290 km) to the west, the Saugerties Police Department said in a statement on Tuesday.

At the time, police believed her biological parents, Kimberly Cooper, 33, and Kirk Shultis Jr., 32, abducted her, they said. The couple did not have custody of the girl, police said.

On Monday, police said they received a tip about the girl's whereabouts and obtained a search warrant. They said they went to the girl's grandfather's house where they searched for about an hour before locating the child hidden in a makeshift room, under a closed staircase leading to the basement.

Upon removing the step boards, the girl and her mother Kimberly were found hiding in the dark and wet enclosure, police said.

Paislee was taken to police headquarters where paramedics examined her, police told the Daily Freeman, the community's local newspaper. The girl was in good health and released to her legal guardian.

Police arrested her parents and the girl's grandfather Kirk Shultis, 57. They face charges of custodial interference and endangering the welfare of a child.

Police said they interviewed Kirk Shultis Jr. several times since the girl went missing. He maintained that he had no knowledge of her location and told officers that he had not seen the child.