MARIETTA — Jurors in the Waseem Daker trial heard the first testimony Wednesday about DNA evidence in the 1995 murder of Karmen Smith and the nonfatal stabbing of her young son, Nickolas, though not yet about any that links Daker to the crime scene.

At least four current or former GBI scientists took the stand, reviewing for jurors their findings on hair and blood samples found at the Smiths’ east Cobb residence.

Daker, who is acting as his own attorney, disputed the state’s contention that two of the scientists are qualified experts. Superior Court Judge Mary E. Staley allowed the testimony.

Ted Staples, now an assistant deputy director at the Georgia Bureau of Investigation’s crime lab, has worked there since 1986 and told the jury about advances in technologies related to DNA evidence.

“It’s phenomenal what we can do in just the last eight years,” he said.

Prosecutors intend to show later that nuclear DNA tests on hairs found on Karmen Smith’s body link Daker to her killing. Nuclear DNA is taken from the nucleus of a cell and differs from mitochondrial DNA in that it can identify someone to the exclusion of all others except an identical twin, Staples said.

But the ability to do nuclear DNA test on a single hair that has part of the root “didn’t take off until the year 2000 or 2001,” he testified.

Staples also told jurors that blood found on a table and floor in the Smith home was consistent with Nickolas Smith, and blood found on a sweater and shirt in the home was consistent with Karmen Smith.

Sidney Seguin, a forensic biologist at the GBI’s crime lab, said DNA tests on blood from a knife at the scene matched Nickolas Smith.

After Daker questioned Sequin about her education and training, he told the judge he did not believe she was qualified as an expert — but he didn’t ask her any questions during cross examination.

Wednesday marked the sixth day of testimony in the trial. The trial is slated to last three weeks, though it is unlikely that the state will rest its case before next week.

Daker, now 34, was born in Toronto to Syrian parents and is a naturalized U.S. citizen. As a teenager, he interned in the Cobb County Medical Examiner’s office. He was also enrolled at Georgia Tech while still in his teens.

In 1996, Daker was convicted of stalking Smith’s upstairs housemate, Loretta Spencer Blatz, and spent 10 years in prison.

Karmen Smith was 30 and a Delta flight attendant when she was killed in her home in the Hunter’s Trace subdivision off Johnson Ferry Road. Smith and her son lived in a basement apartment at 1580 Old Hunter’s Trace, an apartment where Spencer Blatz had previously lived.

Nickolas Smith, who is now 22, testified on Tuesday about the attack that occurred when he was a kindergartener.