BOSTON -- A man who allegedly dressed up like Santa Claus and dropped his pants at a New Hampshire mall last year faced charges on Monday after he was caught trespassing over the weekend at a Boston hospital.

Richard Mullen, 52, of Malden, was arrested on suspicion of trespassing at Boston Children's Hospital on Sunday. Mullen, who was a volunteer at the hospital for 11 years, was in the infant intensive care unit. When police arrested Mullen, they found a bag containing a red balloon and several wrapped condoms in his possession.

"Mr. Mullen acknowledged that he knew that he was not supposed to be in the hospital. He acknowledged receiving that trespass order," prosecutor Jonathan Tynes said. "He explained to the officers that he was there visiting a friend who volunteers at the hospital. He was there, he stated, to help (his friend) volunteer. He was found to have a visitor's pass with that person's last name written on it."

On Dec. 4, 2005, Mullen was arrested in Salem, N.H., at the Mall at Rockingham Park after shoppers said that they saw him drop the pants of his Santa costume. Mullen was charged with disorderly conduct.

Days later, Mullen was charged with trespassing after he was found inside a student locker room at Raymond High School in Raymond, N.H. Mullen pled guilty to that trespassing charge in January.

"Mr. Mullen was terminated as a volunteer at Children's in early December (2005) when allegations against him were first brought to our attention," the hospital said in a statement.

Mullen was arraigned in Roxbury District Court, where he was held on $1,500 bail.

"This is merely a trespass charge, according to the Boston police report. It's trespassing, and it carries a maximum of 30 days in a house of correction if he is convicted," defense attorney Daryl Malden said.