"A lot of people don't know their serial numbers," she said. "They don't have them written down, and if your firearm is stolen and you don't have the number, if it's recovered later, there's no way to know because there's no way to trace it back."

Whether the serial number is known or not, some people just don't tell the police.

"There's certain times where people choose not to report a gun stolen, so there's no way to truly quantify that particular issue," Frederick said.

Frederick said there is no way to completely stop the theft and sale of illegal guns. But she said the biggest way to combat the problem is to educate gun owners on keeping track of their serial numbers and properly storing firearms in a safe.

Frederick encourages all gun owners to fill out a personal firearms record and store the information in a safe place separate from where the guns are stored.