RADNOR TOWNSHIP, Pa. (CBS) — A Delaware County commissioner facing child porn charges has resigned on Monday, CBS3 has learned.

Radnor Township Board of Commissioners President Philip Ahr was arrested last month on several counts of child pornography possession and distribution charges for images that depict children as infants engaged in sex acts with adults.

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On Monday, Ahr resigned as commissioner effective immediately. Ahr stepped down as president last month.

Investigators say Ahr uploaded and shared images of suspected child pornography through a Yahoo Messenger account. According to police, Ahr used Yahoo Messenger to “sext” with unknown individuals, which involved sexual talk about children.

Radnor Township Board President Arrested On Child Porn Charges

The investigation began after Yahoo flagged the messages.

“We charged him with multiple counts of child pornography,” said Delaware County District Attorney Jack Whelan.

According to the criminal complaint, Ahr used screen names like “Daddy X” and “Daddy XX” to visit chat rooms that cater to pedophiles.

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He sent and received images of young children — some 2 to 4 years old.

Ahr told detectives that had been “sexting” online with people and that the purpose of the chats was sexual in nature, police say.

“The Radnor residents are safe. It is everybody’s responsibility to keep our children safe,” said Radnor Township Police Superintendent William Colarulo.

Police say Ahr told detectives that during one of these conversations, an unknown person sent him about one dozen child pornography images of girls who Ahr estimated to be approximately 13 years old. Some of the images involved female children engaging in sex acts with adult males, said investigators.

Detectives say they found multiple chat logs between Ahr and individuals, dating back to 2013, in which Ahr shared and sought graphic images and videos of children in sexual positions, bondage and engaged in sex acts with adults. According to investigators, Ahr’s collection was mainly comprised of prepubescent girls under the age of 10 years, but also included infants and toddlers.

Police say a portion of the images and videos depicted sadomasochistic sexual abuse, and children being sexually abused by animals.

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In October, the 66-year-old was charged with child pornography possession and child pornography dissemination, sexual abuse of children, and criminal use of communication facility, all third-degree felonies.