Paul Arthur Crafton, an engineering professor at George Washington University for the last 20 years, was identified yesterday by university officials as the mysterious "John Doe" arrested in Pennsylvania this week and charged with the use of bogus names and false credentials in establishing false identities in three states.

At the time of his arrest, Crafton, 59, was teaching simultaneously at three colleges and possessed documents bearing at least 31 identities, five driver's licenses and at least two Social Security cards, according to Pennsylvania authorities.

Trained as a mechanical engineer, Crafton had billed himself to at least four college as an expert in computers, accounting, mathematics, finance and business administration, authorities said.

George Washington University officials became suspicious when they identified photographs of the suspect and were told of a 1983 university identification card found in an apartment the suspect maintained in Lancaster, Pa.

The Pennsylvania Attorney General's office is waiting for identification of Crafton's fingerprints through the FBI before officially confirming his identity. The suspect is being held in the Cumberland County jail in Carlisle, Pa., pending a May 3 preliminary hearing. He faces felony charges of theft by deception, tampering with public records, forgery and a misdemeanor charge of false swearing. The felonies each carry a maximum seven-year prison term and a $15,000 fine.

Crafton, who has taught at George Washington since 1956 and is a tenured professor, was placed on immediate administrative leave yesterday by university provost Harold Bright who said he acted "based on information provided by Pennsylvania" authorities.

According to GW authorities, Crafton earns $21,000, less than half the salary of his fellow full professors, because the school was dissatisfied with his work. This year the salary is $14,000 because he is teaching part time at his request.

On the surface, Crafton's life in Washington seemed routine. No one at the university apparently had any idea of the activities alleged by authorities. He and his wife and two children have lived for nearly 20 years in an unassuming brick rambler home in Regency Estates in Potomac. An aged fishing boat rests on a trailer in the front yard, a row of evergreens obscures the house from the quiet residential lane.

But his neighbors and colleagues found him reclusive. He refused to socialize, or even meet with his eight department colleagues at George Washington University. Often, he would pass them in the hall and pointedly ignore them, said Sam Rothman, chairman of George Washington's engineering administration department.

"He was aloof," Rothman said. "He just wouldn't talk to you. We eat together before our monthly faculty meeting. He'd never join us. He never came to a faculty function."

Wayne Lorance, who has lived one house away from Crafton for 12 years, said that "because he was so unfriendly and reclusive and appeared to be an introvert" no one in the neighborhood knew him.

Crafton's wife, Sonya, reached at home yesterday afternoon, said she was anxious to talk about her husband, but "I have to act on the advice of the lawyer. I can't say anything."

Authorities believe that Crafton was teaching at at least four other institutions under assumed names while holding his faculty position at GW--Towson State University in Maryland, Wagner College in Staten Island, N.Y., and Millersville State College and Shippensburg State College, both in Pennsylvania.

Authorities allege that Crafton's other life, which apparently began at least by 1976, was one of borrowed identities aided by answering machines, multiple telephone lines, a condominium in Rockville and at least one female accomplice. The provost of Millersville State College, who knew the suspect as Peter H. Pearse, said yesterday that a woman answered the telephone for the ficticious companies in downtown Washington and Baltimore when Crafton's references were checked.

What puzzles authorities most is how Crafton acquired the volume of documents found in his apartment in Lancaster, at least some of which apparently are genuine credentials owned by other professors whose name Crafton assumed.

An affidavit filed by investigators from the Pennsylvania Attorney General's office in support of the application for the search warrant of the Lancaster apartment said Crafton's application at Shippensburg State College included a legitimate "certificate of academic record" from Cambridge University in England in the name of John Byron Hext, the name Crafton used while teaching at the college.

"That certificate looked legitimate and it is legitimate," said Kim Daniel, a deputy attorney general. He said it is a bona fide certificate of John Byron Hext, a professor now teaching at MacQuarie University in New South Wales, Australia. "How he got it, we don't know," said Daniel.

Police still are sorting through items Crafton left behind in another apartment he maintained in Shippensburg, Pa., including two large pieces of electronic equipment and pencils imprinted with Towson State University.

Pennsylvania authorities said the first record of Crafton's other life came in 1976, when a credit card was issued to the name Arthur Van B. Holland at the address of a Rockville condominium owned by Crafton. That name surfaced on several credit cards found among the 16 boxes of records discovered in Crafton's Lancaster apartment. A Datsun, registered to Crafton and Holland and leased from the First National Bank of Maryland also was found in Lancaster.

The next alias apparently used by Crafton was that of David Arthur Gordon, a name Crafton used when he applied for a part-time job teaching business administration at Towson State in August 1979. "Gordon" taught at the Baltimore County university until March 1982 when he was allowed to resign after missing at least a third of his classes and because he failed to produce his academic credentials, according to university officials.

Authorities believe Crafton then taught under the name of John B. Hext at Wagner College in the spring of 1982.

He taught five mathematics and computer courses and was scheduled to teach every day. In a June term, he taught two courses, Monday through Thursday.

Shortly before the start of fall classes, he resigned abruptly, according to college officials.

In February 1982, using the alias of a professor at the University of British Columbia in Vancouver named Peter H. Pearse, Crafton apparently answered an ad for a $28,000 a year associate professorship at Millersville State College.

He claimed he was a financial consultant with Monroe and Co., a Washington firm police said does not exist, according to Keith Lovin, the Millersville State College provost.

He also told the college he used to work at a Baltimore firm, the Regent Co., which Pennsylvania authorities said is also ficticious.

He was appointed June 4 and began teaching four courses Aug. 31, according to Lovin.

Following "Pearse's" visit to campus, the dean, who had not met him, telephoned him at the firms he cited. "A woman answered the telephone in the name of the Monroe Company," according to Lovin, and then put "Pearse" on the phone. Later, the Regent Company phone was also answered by a woman who took a message for Pearse, Lovin said.

That same fall, Crafton began teaching computer programming at Shippensburg State, 75 miles away from Millersville, under the name of John Byron Hext. The events that led to his arrest began earlier this month, when the chairman of the computer science department read an academic journal with an article written by the Australian professor of the same name, and informed college authorities.