KNOXVILLE, Tenn. (WVLT) - Family members of missing persons were able to help law enforcement investigate their loved one's disappearance as part of DNA Collection Day.

The Knox County Sheriff's Office and Knoxville Police encouraged folks to go by the event and give a DNA sample.

The information will be entered into the National Missing and Unidentified Persons System Database to help build or strengthen the case.

Families were also able to bring things, like a hairbrush or toothbrush, that might have the missing person's DNA.

"Some of these cases date back 30 plus years, even before DNA technology was available. So it's a great way for us to confirm that that could be their loved one. Things change in terms of height and weight and hair color, but DNA doesn't change and is a concrete tool that we can say, 'yes, this is the person,'" said Amy Dobbs with the Knox County Sheriff's Office.

Dobbs says if you missed today's event, you can always stop by the Sheriff's Office for a free test.