Undated (AP) _ Former U.S. Rep. Pat Swindall, found guilty Tuesday on nine counts of lying to a federal grand jury about a money-laundering scheme, is the 20th person in the last decade to be indicted on criminal charges while serving in Congress.

Rep. Donald E. ''Buz'' Lukens, 58, was convicted May 26 of contributing to the delinquency and unruliness of a minor, a misdemeanor. The Franklin County, Ohio, jury found him guilty of having sex with the girl last November.

Lukens faces up to six months in prison and a $1,000 fine for his conviction, but conviction on the misdemeanor charge does not automatically preclude him from serving in the House or seeking re-election, and he has said he will remain in Congress while appealing his conviction.

Lukens is in the second term of his second stint in Congress. He also was in Congress for two terms from 1967 to 1971.

Rep. Robert Garcia, D-N.Y., was indicted in New York on conspiracy charges in the Wedtech corruption scandal. He was the second Democratic congressman from New York to be indicted for allegedly using his influence on behalf of the Wedtech Corp., a minority-owned New York City machine shop that won no-bid U.S. Army contracts. It has since gone bankrupt.

Mario Biaggi, whose former congressional district abuts Garcia's, was convicted last Aug. 5 of racketeering, mail fraud and accepting bribes from Wedtech in exchange for his Washington influence. Biaggi, 71, resigned his House seat Aug. 6 after nearly 10 terms. He was sentenced to eight years in prison and a $242,000 fine.

Biaggi also was convicted in November 1987 of accepting an illegal gratuity - a paid vacation - for helping an ailing New York shipyard. He was sentenced to 2 1/2 years in prison and fined $500,000 in that case.

In October 1988, Fofo I.F. Sunia, American Samoa's former delegate to Congress, was sentenced to five to 15 months in prison for participating in a payroll-padding scheme that reportedly earned him $39,000. Sunia, 51, a Democrat, resigned his congressional seat Sept. 6.

Other members of Congress indicted since 1978:

-Rep. Harold E. Ford, D-Tenn., charged in April 1987 with bank, mail and tax fraud. No trial date has been set.

-Rep. Bobbi Fiedler, R-Calif., indicted Jan. 23, 1986, along with an aide on charges she tried to buy off an opponent for the GOP Senate nomination in California. The charges subsequently were dismissed by a Superior Court judge in Los Angeles; Fiedler lost the primary.

-Rep. George Hansen, R-Idaho, indicted in April 1983 and convicted one year later on charges of violating the 1978 Ethics in Government Act by failing to report $333,978 in loans and other transactions on his financial disclosure forms. Hansen was freed in October 1987 after serving nearly one year of a five-to-15-month sentence.

-Sen. Harrison A. Williams Jr., D-N.J., convicted in May 1981 on charges stemming from the FBI's Abscam investigation, including conspiracy, bribery, conflict of interest, receiving an unlawful gratuity and interstate travel in aid of a racketeering enterprise.

Williams resigned from the Senate in March 1982. He was paroled from a halfway house in January 1986 after serving nearly two years of a three-year sentence.

Six House members also were indicted as a result of the undercover Abscam investigation, and all served prison terms. They were:

Rep. Raymond Lederer, D-Pa.; Rep. Michael ''Ozzie'' Myers, D-Pa.; Rep. John Jenrette, D-S.C.; Rep. John Murphy, D-N.Y.; Rep. Frank Thompson, D-N.J.; and Rep. Richard Kelly, R-Fla.

-Rep. Claude ''Buddy'' Leach, D-La., was indicted in July 1979 on charges of buying votes in the 1978 election and violating federal campaign finance laws. He was acquitted of some vote-buying counts and the others were dropped, and a federal appeals court dismissed the charges of campaign finance law violations.

-Rep. Joshua Eilberg, D-Pa., indicted in October 1978 on federal charges of illegally receiving compensation to help a Philadelphia hospital get a $14.5 million federal grant. He pleaded guilty in February 1979 and was sentenced to five years' probation and fined $10,000.

-Rep. Daniel J. Flood, D-Pa., indicted in the fall of 1978 on 13 counts of bribery, conspiracy and perjury. His trial on 11 counts ended in a mistrial in February 1979. He resiged from the House in January 1980, citing health reasons, after the House ethics committee accused him of 25 rules violations. In February 1980, he pleaded guilty to conspiracy in a plea-bargaining arrangement and was given a year's probation.

-Rep. Charles C. Diggs Jr., D-Mich., indicted in March 1978 and convicted in October 1978 on 29 felony counts of illegally diverting his congressional employees' salaries to his personal use. He resigned from Congress in 1980 and served seven months of a three-year prison sentence.