Three people indicted in the General Services Administration bribery scandal changed their original innocent pleas to guilty in U.S. District Court this week.

So far 24 people have pleaded guilty and eight have pleaded innocent to charges brought by the U.S. Attorney's Office here in connection with the GSA bribery investigation.

Pleading guilty this week were Manuel M. Cumes, 32, former manager of the GSA store at the Nassif building in Washington; Vincent W. Miller Jr., a procurement officer for the Health Services and Mental Health Administration of HEW, and Ollie V. Smith, 40, former manager of two GSA stores in Washington.

After plea pargaining with government prosecutors, Cumes and Smith changed their innocent pleas on multiple count indictments to pleas of guilty of single charges of conspiracy to defraud the U.S. government. The maximum penalty for the conspiracy charge is five years in prison and a $10,000 fine.

Miller pleaded guilty to a single count of bribery, which carries a maximum penalty of two years in prison and a $10,000 fine.

Prosecutors said their evidence would show that Miller accepted bribes of an AM-FM eight-track stereo set and a television set, that Smith accepted car tires, a washer and dryer, a freezer and a pool table, and that Cumes accepted household furnishings and a dishwasher. The bribes were in return for falsifying records for office supplies that were paid for but never delivered to GSA stores.