The husband of a Dumfries, Va., day-care operator was arrested Wednesday in a federal drug case that spurred speculation and worry across Prince William County after FBI agents descended on the facility.

Ralph Caldwell, 38, whose wife owns Little Angel’s Daycare, was charged with conspiracy to distribute oxycodone, according to court documents unsealed Wednesday. FBI agents allege in the documents that he sold drugs to a police informant near the day-care center, and the informant believed Caldwell stored a gun in the school and at least once drove children in a school van while drinking liquid codeine.

The case burst into public view Wednesday when FBI agents showed up at the day-care center — which, according to court documents and the business’s Web site, occupies two suites at the Dumfries Shopping Plaza, a row of businesses just off Route 1. Prince William County schools sent a tweet advising parents to pick up their children who would be headed there at school because of “enforcement activity” at the day care.

According to an affidavit, a confidential informant told investigators from the FBI and the Prince William County police department that Caldwell had sold drugs — including liquid codeine and Roxicodone — “in and near” the day care for about three years.

The informant told investigators he or she believed that Caldwell kept at least one handgun in the day care, and that he or she had seen Caldwell driving a day-care van with children inside while Caldwell was drinking “pineapple soda that was purple in color,” according to the affidavit. The informant said he or she believed that liquid was codeine, according to the affidavit.

A woman who answered the phone at the day care hung up on a reporter, and efforts to reach the day care’s owner were not immediately successful. An FBI spokesman said Caldwell was arrested at his Locust Grove, Va., home Wednesday.

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