NEW YORK (AP) _ Two packages seized in a drug trafficking case against the wife of the former commander of the U.S. anti-drug operation in Colombia contained heroin, not cocaine as first thought, according to court papers.

Laurie Ann Hiett, wife of Col. James Hiett, surrendered in August on drug conspiracy charges. Field tests had indicated two parcels she allegedly shipped to the United States from the U.S. Embassy in Bogota held 1.2 kilos of cocaine each.

But since then, laboratory tests ``have determined that these packages, in fact, contained heroin,'' prosecutor Lee Dunst wrote in an Oct. 21 letter to Mrs. Hiett's attorney.

Dunst refused Tuesday to discuss the case. But in his letter, he said the fact the evidence is heroin instead of cocaine is ``irrelevant'' because, as an alleged drug smuggler, Mrs. Hiett ``need not know the exact nature or type of drug in her possession.''

Mrs. Hiett, 36, has not been indicted and is free on bail. She has denied the charges. Her attorney, Paul Lazarus, said the new information does not change her defense: that she was unaware drugs were in the packages.

``If she didn't know it was cocaine, she didn't know it was heroin,'' Lazarus said Tuesday.

Mrs. Hiett has agreed to give up her right to a speedy prosecution, in part to allow both sides to pursue a possible plea bargain.

Prosecutors have said that if convicted on the cocaine charges, she faced up to 12 years in prison. Charges involving heroin can carry a stiffer penalty.

An investigation by the Army Criminal Investigation Division in Panama cleared her husband, saying he had ``no prior knowledge'' of the alleged shipments. At his request, he was transferred to Fort Monroe, Va.

Mrs. Hiett became a suspect in May when her name appeared on the return address on one of the two packages, which was seized after a routine search by the Customs Service in Miami.