A longtime Villanova University professor has been charged with hundreds of counts of possessing child pornography, Radnor Township police said Thursday.

Christopher Haas, 60, a tenured associate professor of history and classical studies, was arrested after university officials discovered he accessed pornographic images on a public university computer last month, officials said.

The charges on 415 counts came four years after investigators from the U.S. Department of Homeland Security's Philadelphia office began an investigation into Haas during which authorities allege they found more than 400 pornographic images on the Villanova-issued laptop at his home in September 2012.

No charges against Haas were ever brought. Haas, who joined the faculty in 1988, remained a professor until charges were filed last week.

Villanova officials said Thursday that they were unaware of the federal investigation until last week, when the university's technology department discovered suspicious activity by Haas on the college network.

"Obviously, as the director of public safety for the institution, I want to know about anything that could jeopardize student safety," said David Tedjeske, Villanova's public safety director. "At the same time, I recognize the university is a private enterprise and there are limits to what law enforcement can share with any private organization."

The charges against Haas, which also include 415 counts of criminal use of a communication facility, are tied to the 2012 federal probe. Radnor police said an investigation into the Villanova-related incident was continuing.

Haas was relieved of all his university duties this week, and the process of revoking his tenure had begun, officials said.

Haas's attorney, Scott Godshall, of the Media-based Eckell Sparks law firm, said Thursday that Haas was "devastated." Godshall said the federal case into Haas was closed in 2012. He asked why the four-year-old discovery was revived now.

"They brought charges because they think there is something new," Godshall said, adding that he believes officials revived the 2012 findings "to get probable cause to get an arrest warrant."

In March 2012, Homeland Security investigators first made contact with Haas after discovering his IP address had accessed hundreds of images of child pornography in March 2010, according to information provided by police.

During a visit to Haas' home, the professor told investigators he had once viewed sexually explicit images sent by email that he considered to be "borderline," officials said. Investigators at the time said they searched his computer, where no child pornography was found.

Six months later, in September 2012, Homeland Security agents, in coordination with Radnor police, executed a search warrant at Haas' home.

There, according to authorities, Haas claimed never to have traded child pornography, received emails containing child pornography, chatted online, downloaded child pornography, or saved images of child pornography.

Homeland Security investigators seized his computer, where they found 415 images of child pornography, authorities said.

In October 2012, Haas had gone missing, and Radnor Township police had sought the public's help in finding him, fearing that he was suicidal after he left a note suggesting he might harm himself. State Police found him unharmed shortly thereafter.

A Homeland Security spokesman declined to answer questions Thursday about why Haas was not charged until four years after the 2012 raid or why the university was not notified at the time of the child pornography found on Haas' home computer.

He said the agency would not discuss any details of the case to "protect the integrity of the investigation."

Radnor Police Lt. Andy Block echoed the federal agency's explanation.

Haas remains in custody at the Delaware County Prison, where he is to remain until he undergoes a psychological review before being released.

On Thursday morning, Haas waived his preliminary hearing. He is to be formerly arraigned April 27, according to court records.

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Jeremy Roebuck contributed to this article.