A U.S. Court of Appeals panel ruled yesterday that a woman who lived with burglar Bernard C. Welch, the man convicted of the 1980 murder of prominent Washington physician Michael Halberstam, was liable for more than $5.7 million in damages sought by Halberstam's widow and children.

The three-judge panel upheld a March 1982 ruling by U.S. District Court Chief Judge Aubrey E. Robinson Jr., who found that Linda Sue Hamilton "willingly assisted" Welch in "disposing of the loot" from his numerous burglaries in the area.

Hamilton, who lived with Welch for five years, has never been charged in connection with any of Welch's activities. She has denied knowing that he was obtaining gold and silver jewelry and other items through burglaries.

Halberstam's widow, Elliott Jones, sued both Welch and Hamilton for $81 million in damages after Welch shot and killed Halberstam during a burglary of their Northwest Washington home. Welch was convicted in 1981 of the murder and sentenced to 143 years in prison.

U.S. Court of Appeals Judge Patricia M. Wald said in the opinion yesterday that although Hamilton did not commit any burglaries, she served as his "banker, bookkeeper, recordkeeper and secretary" and " . . . it defies credulity that Hamilton did not know that something illegal was afoot."