DENVER (CBS4) – Each year thousands of firearms go missing in Colorado. State lawmakers are considering a bill that would make it a crime for a gun owner not to report their firearm missing.

A mother whose daughter was shot and killed while walking her dog in Denver’s ballpark neighborhood last summer is among those supporting the bill.

READ MORE: Mother Of Denver Murder Victim Isabella Thallas Painfully Remembers Her ‘Little Chic Hippie’

“I feel compelled to make a difference,” said Ana Thallas.

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The gun used to kill her daughter, Isabella, had been stolen and not reported. Thallas says she would do anything for just 5 more minutes with her daughter but instead, she says all she can do now is try to spare other moms her pain.

“I guess this was just my way of remembering my daughter,” she said.

Isabella Thallas (credit: Ana Thallas)

Michael Close, 36, faces several charges including first-degree murder for the shooting that killed Isabella and seriously injured her boyfriend. According to the Denver Police Department, Close, a friend of a Denver police officer, took the rifle from the officer’s home without the officer’s knowledge or permission. Upon learning his rifle was missing and that it may have been used in the homicide, the officer notified investigators that the rifle belonged to him.

State Sens. Sonya Jaquez Lewis and Jessie Danielson are the sponsors of a bill that requires law enforcement to enter information about the lost or stolen firearm into the National Crime Information Center Database and report the information to the Colorado Bureau of Investigation.

Jaquez Lewis says it would help law enforcement track missing weapons before they’re used in a crime.

“This is about protecting the public from something that could do harm. And we know that lost and stolen weapons are being reported in crimes. So we know that this could keep our communities safer,” said Jaquez Lewis.

Republicans challenged that argument.

READ MORE: ‘Better Than Going To A Gravesite’: Mural Immortalizes Isabella Thallas

“The gun is already missing. It’s already in the hands people we don’t want it in. How is that going to reduce gun violence?” asked State Sen. Jim Smallwood.

Smallwood says the bill will turn victims into criminals.

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“We’ve set a new bar in creating criminals in our state. Who are the criminals? Somebody who got robbed,” he said.

Under the bill, gun owners who fail to report a missing weapon within five days could be charged with a petty offense and fined $25. If it happens again, they could face a misdemeanor charge and $500 fine.

Jaquez Lewis says the bill is meant to incentivize what should already be common practice.

“If we can save the life of any children, any teenagers, anyone in Colorado with a bill, we need get done,” she explained.

Jaquez Lewis plans to name the bill after Isabella Thallas, a gesture that Ana Thallas says is bittersweet.

“It’s all a mother could ask for, a mother in my position,” Thallas said.

MORE NEWS: Ballpark Shooting: Michael Close Pleads Not Guilty By Reason Of Insanity In Death Of Isabella Thallas, Family Says

The bill got initial approval in the Senate on Tuesday.

Shaun Boyd