WATCH: Take a Tour of the Orange County Forensics Lab

From proving someone was driving drugged, to calibrating Breathalyzers, to collecting and extracting DNA from murder scenes, Orange County's forensic crime Lab is one of the biggest in the country.

County officials touted the Orange County Crime Lab with a press tour Wednesday in honor of National Forensic Science Week.

“We have a nationally and internationally accredited crime lab here,” Orange County District Attorney Tony Rackauckas told assembled reporters. “The science works in a lot of different ways... it’s not just DNA, it’s toxicology as well. If a burglar uses a pair of pliers or a tool to break open a door, that tool will leave identifying marks, most likely. A bullet can be identified as coming from a particular gun.”

He lauded the 140 professional and support personnel who staff the $18.4-million-per-year forensics laboratory that serves 100 different law enforcement agencies.

“When we have to go to court, it’s important that these are well-qualified scientists who are above reproach,” Rackauckas said.

Orange County Sheriff Sandra Hutchens agreed.

“Juries rely on the scientific evidence probably more than any other evidence in a case,” she said.

Crime Lab Director Bruce Houlihan led the tour through the six floors of the crime lab. In the toxicology and forensic alcohol bureaus, scientists are not only helping to convict drugged and drunk drivers, but they’re also conducting original scientific research in the field.

For instance, Assistant Director for Forensic Toxicology Jennifer Harmon said the lab records blood levels of various prescription drugs and marijuana and cross-references the levels with the investigative reports that describe the suspect’s behavior. This research will help develop standards for legal blood limits of marijuana, for instance, now that it’s legal in some states recreationally, she said.

In the DNA bureau, the forensic scientists pull DNA from all sorts of items. They demonstrated their techniques for reporters Wednesday using a bloody shirt, a beer bottle and a pillowcase.

When analyzing DNA for the Combined DNA Index System, there’s plenty of material to work with because the sample is collected from suspects in custody through a mouth swab. This DNA can be matched to other potential DNA collected at crime scenes within minutes, scientists said. The CODIS contains about 9,000 samples from Orange County alone, which police all over the country can cross-reference to solve cold cases, Rackauckas said.

But for dealing with the tiny amounts of DNA collected at crime scenes, the OC Crime Lab has two DNA-extracting robots that can analyze such samples in three hours -- shaving nine hours off the fastest time in which a human scientist could do the work, said Forensic Scientist Corrie Maggay.

Other bureaus include vehicle investigation and “Criminalistics,” in which scientists match bullets to guns and analyze tool marks. The Identification Bureau looks at tire track, footprints and fingerprints. All the bureaus do crime scene investigation and collect evidence to analyze, Houlihan said.

And in addition, the forensic scientists also testify in court about their findings. In 2012, Houlihan said, OC Crime Lab staffers spent 1,700 hours testifying.