Throughout October, November and December, "Meghan Thomas" spent a lot of time in Internet chatrooms frequented by children, saying she was an 11-year-old girl in Pittsburgh.

She used the screen name "meghan15222" -- the number was her ZIP code. She showed off a picture of herself in a modeling competition and said her birthdate was Dec. 14, 1994.

At least the Dec. 14 part was authentic.

But the person chatting in those rooms was actually born on that date in 1947.

"Meghan Thomas" was really Roger Millspaugh, 57, a convicted child rapist from Lawrenceville just released from prison who had been accessing the Internet dozens of times from the library at Duquesne University.

The FBI suspects he was trolling for potential victims.

"It appears that Millspaugh is representing himself as an 11-year-old juvenile female in the Pittsburgh area, and is making an effort to access several different online communities, forums and chat rooms with a concentration on making contacts with juveniles and young children," wrote FBI Agent Eric Fiterman in a search warrant affidavit.

Millspaugh's brief stint of freedom is over, for now.

Last week a federal judge sent him back to prison for two more years for violating his probation on a previous child pornography conviction.

Now federal prosecutors are examining his Internet use at Duquesne and evidence seized from him during his Jan. 7 arrest at the Light of Life Mission on the North Side for more child-porn violations.

Prosecutors and the FBI won't discuss pending cases, but there is little doubt that they consider him to be a dangerous predator.

"Millspaugh is a registered sex offender who has previous incarcerations and yet has continued to offend," said U.S. Attorney Mary Beth Buchanan. "It's important that Millspaugh be incarcerated because of the obvious danger to the community he presents."

A Megan's Law violator, he has history of sexual assault and spent 20 years in state prison for kidnapping and raping two Lock Haven schoolgirls in the 1970s.

When agents arrested him on the North Side, they said he was carrying a nylon bag filled with child-sex fantasies he'd written, child modeling photos, a handwritten chart with detailed body measurements of young girls and printouts of children's events around town.

He was also carrying an article from The New York Times about a school district in Texas that has begun monitoring children with computer chips to track them when they get on and off school buses.

The materials were similar to those found in Millspaugh's possession in 2001, for which he ended up sentenced to 41 months in federal prison.

Millspaugh most recently lived on Warenberg Way in Lawrenceville when he was indicted in 2001, but he is originally from East Freedom, near Altoona, and has a notorious past.

In July 1971, when he was 24, he was living at the Passmore Hotel in Philipsburg, Centre County, when he attacked an 8-year-old girl living there with her parents. He grabbed the girl as she was heading upstairs, forced her into his room, tied her hands and raped her at knife-point.

According to the FBI, he then took the girl to another floor to throw her out the window, but he couldn't get it open. He left her in a bathroom, where she made enough noise for her sister to find her.

Millspaugh was sentenced to 2 to 6 years for that crime at Rockview State Prison, but was paroled on Nov. 21, 1973.

Three months later, he struck again.

On Feb. 15, 1974, police arrested him for kidnapping two Lock Haven Junior High School girls, ages 13 and 14, as they walked home from school. Millspaugh forced them into his car at gunpoint, drove them to a wooded area, tied their hands and feet and placed them on the ground in the snow. He then raped both girls and left them tied to a tree.

The girls were later found walking along a rural road near Renovo in Clinton County, where a trucker picked them up and flagged down state police.

This time Millspaugh was sent to prison for 20 years. In jail he kept a journal in which he wrote stories about children being raped; that diary would later be used as part of the basis for a new prison term.

After his release on March 2, 1999, he moved to Pittsburgh. He was supposed to register as a sex offender under Megan's Law, but he didn't. Pittsburgh police arrested him on June 10, 1999, and he was sent back to prison.

During that June arrest, police found a black bag filled with child pornography downloaded from Carnegie Library and a child-sex story. Authorities at the state prison also found the journal he kept there. The U.S. attorney's office presented it all to a grand jury, which indicted Millspaugh in 2001.

His public defender, Penn Hackney, argued that the charges should be tossed because he said the prison stole the journal and because Millspaugh's pictures of naked children weren't really child porn. Hackney, who described Millspaugh as a "so-called" pedophile, also argued that any jury hearing the case shouldn't be told about Millspaugh's history of rape.

In the end, Millspaugh pleaded guilty and went to prison again. But he also got credit for time served on his Megan's Law violation and on Sept. 29 was released on federal probation.

And that's when the employees at Duquesne University's Gumberg Library saw him looking at pictures of little girls in their underwear on the computers.

They told him to leave several times, but he kept coming back. When he returned on Dec. 22, university police cited him for defiant trespass and escorted him off campus.

The university's technology staff preserved his online history and the FBI later obtained a search warrant for his accounts and his backpack.

Among his collection of items was another story he had written in longhand about a 9-year-old girl having sex for the first time, which he had later posted on his own Web site below a picture of a scantily-clad child model.

There also was a newspaper article about a children's event at the Carnegie Science Center; a printout from the Carnegie Library Web site about activities there for toddlers and babies; a handwritten list of child porn pictures online; and a guide on how to circumvent Children's Internet Protection Act filters.

And there was that strange handwritten chart, in which he carefully wrote down such figures as hip and chest measurements for little girls at various ages.

Millspaugh isn't in jail for any of those materials, however, but for failing to check in with authorities. After his release in September, he was supposed to report to federal probation officer Wendy Brown every week.

He didn't, and Chief U.S. District Judge Donetta Ambrose gave him two more years behind bars, the maximum under the law.

After the two years is up, however, there is no more probation. Millspaugh will be a registered sex offender under Megan's Law, but police nationwide have had well-publicized problems keeping track of Megan's Law offenders.

That fact hasn't been lost on federal prosecutors or the FBI, who are examining his Internet use and his weird collection of materials.

A new indictment could keep him behind bars for at least a few more years.