U.S. District Judge John C. Coughenour on Thursday authorized the taking of blood, saliva and handwriting samples from Ressam.
The 32-year-old Algerian native has pleaded innocent to conspiring to commit a terrorist bombing, smuggling explosives, possessing an explosive device and making false statements. He faces trial July 10 in Los Angeles.
Investigators want to compare his DNA with a stain found on some burned pants that were seized from Ressam's apartment in Montreal after he was arrested Dec. 14 in Port Angeles, where Customs agents said they found the explosives EGDN and RDX in his rental car trunk.
Tests on the pants and on tennis shoes found in the apartment show burns and holes were caused by chemicals used to make EGDN, and traces of both explosives were found on the same clothing, government lawyers said.
FBI agents found Ressam's right leg bore recent scars that appear to be from burns and the judge authorized a medical examination.