DEXTER — State police and the National Center for Missing and Exploited Children have opened a search to check on the welfare of two children from Dexter.

Nathan Daniels, who will be 2 in October, and his sister, Abigail Gosier, 3, are believed to be with their mother, Melissa M. Gosier, 28, and an ex-convict who is said to be their father, Richard E. Daniels, 30.

Senior Investigator Michael C. Pastuf, who is with the state police at Watertown, said police have been told the children are not being properly cared for.

According to a bulletin put out by the Center for Missing and Exploited Children, the children were last seen Thursday in Dexter. They are believed to have been taken to Poughkeepsie, and were likely traveling in a green 1995 Chrysler Cirrus four-door sedan with New York license DEZ-4318.

Mr. Pastuf specified there are no allegations of abduction, but the children "are considered endangered." Other police agencies are assisting, he said.

Mr. Daniels was sentenced in 2006 in Jefferson County Court to two years in state prison and five years' post-incarceration supervision for second-degree counts of attempted assault and attempted burglary. He was released on parole Jan. 18.

Birth announcements for the two children in the Watertown Daily Times listed Ms. Gosier as their mother, but listed no father.

Nathan Daniels has brown hair and brown eyes, is 2 feet tall and weighs 27 pounds. Abigail has blonde hair and blue eyes, is 2 feet tall and weighs 30 pounds.

The Times birth announcement for the girl had her first name spelled "Abbigail."

Any information can be directed to state police at 782-2112, or to the National Center, toll free, at 1 (800) 843-5678.