A New York State Police detective spotted her "tiny feet" in the "cold and wet" hidden space.

Paislee Shultis was allegedly abducted by her biological parents after they lost custody of her in 2019 - and police believe they have kept her hidden in the house where her paternal grandfather lives in Saugerties in upstate New York.

A tip-off led police to the address on Monday night where an officer, using a torch, spotted a small piece of blanket through a crack in the staircase.

"Detectives used a tool to remove several of the wooden steps, and that is when detectives saw a pair of tiny feet," police said.

"After removing several more steps, the child and her abductor were discovered within."

Paislee and a 33-year-old woman were discovered in a small room under the stairs, described as "small, cold and wet".

Police say the girl appeared to be in good health.

A woman was arrested and charged with custodial interference and endangering the welfare of a child.

Two men at the house were also arrested and charged with "felony custodial interference" and "endangering the welfare of a child".