(CNN) -- The chief operating officer of the National Children's Museum was arrested Tuesday and is charged with distributing child pornography over the Internet, authorities said.

Robert A. Singer is accused of sending images depicting child pornography to people he believed to be a 12-year-old girl and her 33-year-old mother, according to a statement issued by U.S. Attorney Michael Garcia of the Southern District of New York.

In reality he was communicating with an undercover detective for the New York Police Department.

Some of the pornographic images were sent from Singer's computer at the museum, according to an affidavit filed in support of the charges by a special agent who investigates child pornography and child exploitation for U.S. Immigrations and Customs Enforcement.

The Washington museum posted a message on its Web site saying officials there are "horrified" by news of Singer's arrest. They reported that he has been suspended from his post, effective immediately, and is barred from the property.

Singer, 49, was arrested at his home in Falls Church, Virginia, by federal agents, according to the prosecutors' statement. Authorities allege he engaged in several instant messaging "chats" and e-mail communications with the undercover detective, posing as the woman and her daughter, from August to September.

He is charged with five counts of distributing child pornography in interstate commerce. If convicted on each count, he would face a sentence of up to 140 years in prison -- up to 20 years for the first count and up to 40 years for each additional count, prosecutors said.

Singer allegedly initiated contact with the undercover detective, posing as the mother, in an America On Line chat room called "Cuties." The chat room attracts people who "are known to trade in pornographic images, including child pornography," according to an affidavit filed in the case by a special agent who investigates child pornography and child exploitation for U.S. Immigration and Customs Enforcement.

"On five separate occasions in August 2007, Singer sent several images of child pornography over the Internet to the mother and the daughter, including images depicting sexual acts between minors and adults and images depicting known victims of child exploitation," prosecutors said.

In his communications with the supposed daughter, Singer pretended to be a 15-year-old boy, authorities said. In August 2007, he sent her two images featuring child pornography, according to the affidavit, with the instruction, "just delete it when you are done."

A search of Singer's AOL account activity showed that from July to September, he sent about 80 images featuring child pornography to people including the detective, authorities said in the statement. Also, the search revealed that he had received about 10 images and one video depicting child pornography.

Singer was expected to appear before a U.S. magistrate judge later Tuesday.

He is identified in the complaint as a spokesman for the National Children's Museum, but a spokeswoman who asked not to be identified said he was promoted to chief operating officer within the past few months. He has been employed by the museum for four years, she said.

In a written statement, the museum said it was notified by the Department of Homeland Security and ICE of Singer's arrest. "We are horrified by the charges," the statement said. "This news is deeply upsetting to the National Children's Museum family."

"As its essence, the National Children's Museum is about enriching the lives of children," the statement said. "We are educators, child advocates and parents. Anyone who does anything that might endanger the welfare of a child has no place here. Harming children is against everything we stand for as an organization and as individuals."

The museum, formerly known as the Capital Children's Museum, has been closed to the public since 2004, and operates from administrative offices, the statement said. A new facility is being built and is scheduled to open in 2012. E-mail to a friend