Late last year, Crystina J. Stephens checked out 483 books from Prince George's County public libraries. Most of the tomes were college textbooks on chemistry, biology and math.

Stephens, 20, wasn't looking to expand her horizon of knowledge. She was trying to fatten her bank account.

Stephens used fake identification to obtain seven library cards under different names. Stephens and her boyfriend, Larry L. Miler Jr., 23, then sold or tried to sell the books she'd checked out to used-book stores.

"She said she needed money. She thought it would be a good way to make money," said Prince George's Assistant State's Attorney Doyle L. Niemann.

Authorities closed the book on the couple's scheme yesterday, when Stephens and Miler both pleaded guilty to aggregate theft over $500, a felony.

Circuit Court Judge Michael P. Whalen ordered Stephens and Miler to jointly pay $20,000 in restitution to the public library system. Whalen sentenced Stephens and Miler to two years in jail, then suspended the sentences.

"I've never seen anything like this," said Sgt. Chris Purvis of the Hyattsville Police Department, who broke the case.

Purvis started tracking the book bandits early this year when a library system employee called to alert him that she had noticed something suspicious.

The woman, in charge of collecting library card applications from the county's branches, told Purvis that a woman had checked out 74 books she hadn't returned. The employee had checked the woman's library card application and found her signature was virtually identical to that of an applicant with a different name.

Purvis learned that the library system was missing 483 books, borrowed under seven cards. He said he deduced that whoever was taking the books was reselling them.

The sergeant went to BookHolders, a used-book store in College Park, across the street from the University of Maryland. Purvis showed manager Louis Verde a list of missing library books and asked him to call if anyone came in trying to sell any of the titles.

Stephens and Miler came into the store Feb. 11 to sell some books. Verde called Purvis, who was on Route 50 in Bowie driving home. Purvis told Verde to stall them. The sergeant turned around, activated the lights and siren in his unmarked sedan and reached the bookstore in less than 20 minutes.

Stephens and Miler both confessed. Purvis learned that they had removed library stickers from some books and marked "Used" on the top of the pages of others to conceal library codes.

After yesterday's hearing, Miler said, "I'll never break the law again." Stephens declined to comment.