Since 2010, Jan and Bill Smolinski have made the long trip to Washington to lobby for "Billy's Law," named after their son who disappeared nearly two decades ago. And each year, it failed to pass. That finally changed this week – after the family of Gabby Petito, whose case grabbed international headlines, lobbied Congress.

"We have tried to make something positive out of the most horrific experience of our lives," Jan Smolinski said Friday. "And when this is signed into law and helps others, good will have come out of bad."

When Billy Smolinski vanished back in 2004, billboards flooded Connecticut highways. Three years later, News 12 Connecticut profiled the dramatic twists in Smolinski's case.

But the search was hampered by a lack of coordination between police agencies and a slow response from Waterbury police.

"We knew there was something wrong," said Smolinski's father Bill. "Immediately."

On Wednesday, Congress gave final approval to Billy's Law, which streamlines the process for missing persons cases involving adults.

Each year, 600,000 people are reported missing in the U.S., while 4,400 bodies go unidentified, according to the National Missing and Unidentified Persons System (NamUs). Billy's Law will potentially match them up, combining the resources of NamUs with the FBI's National Crime Information Center (NCIC).

Billy's Law also requires police departments to promptly report missing persons and unidentified remains to NamUs.

"Had this law been in place, the Waterbury Police Department might have taken this case more seriously and done the work in the early days," said Sen. Chris Murphy (D-Connecticut), who first introduced the legislation in 2009.

"Billy's Law" stalled for years – until last summer, when Gabby Petito's disappearance grabbed international headlines. The 22-year-old social media influencer from Long Island was found dead in Wyoming. Petito's boyfriend, Brian Laundrie, killed himself, according to an autopsy. In a notebook found with his remains, Laundrie confessed to killing Petito.

Petito's parents joined the effort to finally pass Billy's Law because of their own frustrations with law enforcement.

"I was naïve," said Nichole Schmidt, Petito's mother. "I thought, 'Hey, this is simple, right? We go to the police station, and you report your loved one missing and the police do their work.'"

Unlike Petito, Billy Smolinski has never been found.

"We like to think Billy is smiling and happy to know that his family has not given up searching for him, and that during our search, we have managed to make the country a safer place for all Americans," said Jan Smolinski.