Former San Francisco Police Department criminalist Deborah Madden made a brief appearance as a witness this morning in San Francisco Superior Court, where she asserted her Fifth Amendment right not to incriminate herself during a hearing in a misdemeanor DUI case.The case is the first in which Madden, 60, was called as a witness since the drug lab scandal broke in early March. Attorneys in the case are conducting pretrial hearings, and are scheduled to begin trial next week. The case involves a 41-year-old man, Robert Thomas, arrested for DUI in May 2008.Defense attorney Maria Lopez wanted to call Madden, who is accused of stealing small amounts of cocaine from the lab last year, as a witness, in order potentially cast doubt on the results of Thomas’ alcohol test.On May 13, 2008, Madden ran the last routine test on the breath alcohol-testing instrument prior to it being used to test Thomas, in order to see if it needed to be recalibrated, and it did not, according to prosecutors.After Madden asserted her right against self-incrimination today, Judge Newton Lam ruled her unavailable to testify in the case.Lopez then told the judge she is considering calling Madden’s supervisor at the lab, as well as Madden’s sister, who reportedly found cocaine at Madden’s San Mateo home in December, to testify. A decision on those potential witnesses has not yet been made.Madden,a former civilian employee of the Police Department, went on leave in December and officially retired March 1. Police Chief George Gascon on March 9 ordered drug testing at the lab temporarily halted.Since then, prosecutors have been forced to dismiss hundreds of drug cases, but have said they hope to re-file as many as possible after evidence is retested by outside labs.