MONTPELIER, Vt. (AP) — A former Vermont teacher serving a 25-year-sentence in federal prison after pleading guilty to child pornography charges involving some of his Bradford students has died in prison.

The U.S. Bureau of Prisons said Richard Foster, 57, died Feb. 9 at the Federal Correctional Institution in Petersburg, Va.

U.S. Bureau of Prisons spokesman Chris Burke said he did not know the cause of Foster’s death.

Foster, who had taught in Orange County schools for two decades before his September 2007 arrest, was charged with a variety of offenses after police found sexually explicit photos Foster sent by cell phone to a former student who had moved to Florida. Investigators subsequently discovered additional sexually explicit images involving another sixth grade student.

He was initially charged with a variety of state offenses. About a year after his arrest Foster pleaded guilty to two federal child pornography charges. He was later sentenced to 25 years in prison.

‘‘It’s an end to a sad chapter in Bradford’s history,’’ Mark Johnson, the chairman of local school board when Foster was charged told the Caledonian Record (http://bit.ly/VW9nlg).

Even though it has been more than five years since Foster was arrested, Bradford residents are still coming to terms with the notion that something so horrible could happen to two children in their small town, Johnson said.

‘‘I don’t know that you heal. You carry on. You care for the victims and I think the town has supported those folks,’’ Johnson said.

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