A former officer of the American Security Bank, who acknowledged taking $65,000 from an 62-year-old customer and diverting it to his own use, pleaded guilty in federal court yesterday to making a false statement to a bank.

Michal D. Barnes, 37, of 3109 Mount Pleasant St. NW, told U.S. District Judge Barrington D. Parker that he used the money to defray his personal debts.

A spokesman for American Security said that Barnes, who worked at the bank for three years, was dismissed in April. The spokesman also said Barnes had repaid the customer, a 62-year-old woman, in full.

Barnes faces up to two years in jail or a $5,000 fine or both. Parker, who accepted Barnes' guilty plea, scheduled sentencing for Nov. 5.

Assistant U.S. Attorney J. Herbie DiFonzo said in court that the government could prove that Barnes told the woman he had set up an investment portfolio for her and gave her fraudulent documents as purported proof.

The woman gave money to Barnes on three occasions, all in checks written out to him, in April and September of 1980 and last February for a total of $65,000, the prosecutor said. He said the scheme was uncovered when an accountant for the woman called the bank and was told they had no record of her investments or any other business with the bank.

The false statement charge against Barnes stemmed from his obtaining the signature of another bank official on an agreement for a nonexistent trust. That bank official had no knowledge of Barnes' activity, DiFonzo said.