A 56-year-old Philadelphia man with a long white beard calling himself "dirty old Santa" was arrested Wednesday at an ice cream shop in Ridley Township where he planned to meet a 14-year-old girl for sex but instead was confronted by undercover police, authorities said.

William T. McKinlay, of the 900 block of Marcella Street, the Summerdale section of the Northeast, was charged with attempted statutory sexual assault, attempted involuntary indecent sexual intercourse, and related offenses. He was being in held at the Delaware County Prison on $250,000 bail.

Investigators determined that McKinlay, who is active in the theater scene in Philadelphia, worked as a seasonal employee at Macy's in the city but could not confirm his exact position.

In December, McKinlay posted a photograph on his Facebook account of himself dressed as Santa at "Macy's Santaland" with the Center City street character known as Philly Jesus sitting on his knee.

On April 12, Officer Tim Kearney of the Ridley Township Police Department, responded to an online advertisement title "young uns – m4w (NE)" posing as 14-year-old "Stephanie" and McKinlay replied to her, police said.

McKinlay allegedly began to have sexually explicit conversations with who he believed to be an underage teen. Police said he explained to "Stephanie" how to masturbate and ordered her to do her "homework." He sent her a picture of himself with his tongue poking through his fingers and explained how he could perform oral sex on her.  He referred to himself as "dirty old Santa," police said

McKinlay allegedly said he wanted to see her naked and teach her about sex. They made arrangements to meet at the ice cream shop. He told her to wear a sleeveless T-shirt, shorts, sneakers, and nothing else, police said.

When McKinlay arrived at the ice cream shop, he was met by Officer Kearney along with other law-enforcement officials. He was arrested without incident.

"The allegations against McKinlay are a reminder to parents of the need to be vigilant in protecting children from those who relentlessly prey upon them on the Internet," said Delaware County District Attorney Jack Whelan.

In January, McKinlay pleaded guilty in a Montgomery County Common Pleas court to harassment by lewd communication and unlawful dissemination of intimate images involving a married Upper Dublin woman that he had sex with. The explicit photos and video of her were taken without her permission. He was sentenced to probation.