Thomas C. Pulliam Jr., the former Prince George's County bank officer charged with receiving part of a $25,000 loan he made in the name of a fictitious person, had previously obtained a $4,800 loan under the same fake name when he was a loan officer at the Bank of Bethesda, the government's chief witness testified in federal court here today.

Gordon R. Butler, who testified after agreeing to plead guilty to a reduced charge for his role in the $25,000 loan from the Jefferson Bank and Trust Co., testified that Pulliam approved the Bethesda loan in the name of "Robert Baker." That was an alias that Butler used as a private investigator and the same fake name Pulliam later used in making the loan at Jefferson, where Pulliam was executive vice president.

Butler told the jury that while at the Bank of Bethesda, Pulliam made two loans in the name of "Robert Baker," the first in 1978 for $3,500, which Butler used and repaid, and another in 1979 for $4,800, which went to Pulliam.

"I cashed the ($4,800 Bank of Bethesda) check and gave the proceeds to Mr. Pulliam," Butler testified. "Mr. Pulliam used the money to purchase a house, I believe." Butler said Pulliam later repaid the $4,800.

In the Jefferson loan, the government contends that Pulliam used $10,000 of it to help finance his half-interest in a satellite television antenna business he was starting with another bank customer.

Jefferson, a small, two-year-old bank in Capitol Heights, has among its stockholders many prominent Prince George's businessmen and politicians, including County Executive Lawrence J. Hogan, Planning Director Charles A. Dukes Jr. and Washington Bullets general manager Bob Ferry. State and federal regulators strongly criticized the bank's lending procedures earlier this year and the bank says it has corrected the problems.

The three-count indictment against Pulliam charges him with conspiring with Butler to fraudulently obtain the $25,000 loan in May, 1981 by using the fictitious Baker name and with submitting false financial information to get the loan.

A crucial issue is whether Pulliam knew at the time that "Robert Baker" was a fake name used by Butler. Pulliam's attorney has said in court that Pulliam had "no reason" to doubt that "Robert Baker" was a real person.

Stanley J. Reed, Pulliam's lawyer, spent most of his lengthy cross-examination of Butler today attempting to discredit his story.

Butler testified that he supplied phony financial information under a second fake name, "Robert Russell," to help a partner obtain another $25,000 loan from Jefferson. But, Butler said, the loan was approved by Pulliam, who directed him to supply the phony financial information to help Butler's partner qualify for the loan. His partner later repaid the loan, Butler said.

Butler, a Northern Virginia-based private investigator, said Pulliam approached him in the spring of 1981 to help get two Jefferson bank loans to finance the satellite antenna business Pulliam was starting.

Pulliam first gave Butler a $15,000 loan in Butler's real name on Apr. 1, 1981 and Butler turned over the full amount, in the form of a $12,000 cashier's check and $3,000 in cash, to Pulliam, Butler testified.

A month later, Butler said, he agreed to help Pulliam get a second loan for the $25,000, but Butler said he sugested that Pulliam make it in the name of "Robert Baker," and Pulliam did. Butler said he used the alias because he did not want to be liable for more money that was actually being used by Pulliam.

Butler testified that he converted part of the $25,000 check into a $10,000 cashier's check made payable to Pulliam. Bank records show that $10,000 was deposited in the account of Pulliam's antenna business that same day. Butler said he used the remaining money to pay off the $15,000 Jefferson loan.

Butler said he became involved in the two loans as a favor to Pulliam. "Mr. Pulliam was a very good friend of mine," who granted him several loans to help his business since the early 1970s, Butler testified. "He helped me when no (other banks) would trust me to pay my money back", Butler said.