BALTIMORE -- The trial of the man accused of killing a Baltimore city police officer was back in court Wednesday after questions were raised about the forensics evidence in the case.

DNA, Gun Focus Of Grimes Trial

Brandon Grimes is accused of killing Baltimore city police Officer Troy Chesley Sr. in January 2007. On Wednesday, the defense tried to poke holes in the prosecution's case after a recent shakeup at the city's crime lab.

"They had the DNA. They had his swabs. They had everything. If he were the guy, they -- I would think -- be able to say so," said Grimes' attorney, Roland Walker.

Walker expressed concern over DNA evidence introduced in court on Wednesday.

Baltimore City Crime Lab DNA Technical Leader Rena Santos testified Wednesday that she called for the employee database test that led to the firing of former crime lab director Edgar Koch.

She talked about recent problems within the lab concerning DNA, saying that in 12 open cases, including Grimes', employee DNA was recently found. She said that's common in cases, but should have been discovered long ago.

According to court testimony, Victor Meinhardt, a firearms specialist who secured the alleged murder weapon at the crime scene, somehow got his DNA on the gun.

Santos said that when original DNA tests were done on the gun allegedly used in the crime, they revealed two unknown forms of DNA. But almost a year later when tests were done again using employee DNA, one of the matches came up for Meinhardt. She said the other sample was a partial, meaning they can't say if it is or isn't Grimes' DNA.

Grimes' attorney questioned Santos about the DNA find, calling it "serious." Santos said it's a common situation and that it in no way affected the other DNA found on the gun.

Another lab tech who analyzed DNA at the scene said she found Grimes' and Chesley's DNA all over the crime scene. She said the partial sample that was found on the gun definitely ruled out all other suspects in the case except Grimes, and said she didn't feel comfortable dismissing him as a match.

The state rested Wednesday evening. The defense will take over Thursday morning.