Lost or stolen guns often times go unreported.
If used in a crime, this makes tracing their origin or catching criminals connected to the weapon more difficult and sometimes impossible for law enforcement.
NBC 7 Investigates and more than a dozen NBC stations across the country teamed with the nonprofit journalism organization The Trace to comb through more than 800,000 stolen or missing gun records.
"Missing Pieces: Tracing Stolen Guns in America" is an eye-opening look at whose hands stolen and lost weapons end up and what heartbreak befalls those who wind up in their sites.
Missing Pieces: Investigation Shows Impact of Stolen Guns
While with the Airforce, serving in Iraq, Dylan Park-Pettiford said he carried a gun at all times and knows the responsibility that comes with it and the consequences of carelessness.
"Emotionally you know, for my parents, it was completely devastating," Park-Pettiford said.
According to data obtained by NBC 7 Investigates, a stolen Glock model 23 handgun taken from Riverside County in January 2010 is the same gun used two years later to wound a San Jose police officer and kill Dylan's brother Rory.
"I don't worry that more families like mine will suffer I know that more families like mine will suffer," Park Pettiford said.
Based on the crime data obtained by NBC 7 Investigates Park-Pettiford is one of 63 Californians since 2010, killed by someone using a stolen gun. The data obtained also indicates, in that time period, 1,570 violent crimes were committed in the U.S. with stolen guns. Those crimes include carjackings, kidnappings, stick-ups at stores and banks, accidental shootings, and mass shootings.
“It's still pretty sickening that something like this could be occurring and there's almost no talk about it,” Park- Pettiford said.
Stolen Pieces: Tracing Stolen Guns in America
There is little talk and limited information about stolen or lost guns. At the ATF National Trace Center in Martinsburg, West Virginia, agents are charged with tracing guns used in crimes, but without a national database their methods may seem archaic.
"So what we're doing is we're only responding to requests for guns that are recovered in crimes to try to identify that first retail purchaser,” ATF Trace Center Spokesman Neil Troppman said.
The data obtained for this investigation is more pieces than the whole puzzle but the data shows more than 204,000 guns were stolen, over 23,000 of those connected to criminal investigations and at least 4,800 stolen weapons were recovered in California.
In San Diego County, nearly 200 stolen guns were recovered in connection with crimes, including two attempted murders, 15 assaults, and 40 burglaries.
The data came from over 1,000 law enforcement agencies in 36 states and Washington D.C. The data includes records from the San Diego Police Department and the San Diego County Sheriff's Department.
Click here to see more on this national investigation.
"These guns are still being recovered,” Kevin O'Keefe of ATF Operational Intelligence said. “Crime guns are not perishable. They don't wear out and disappear.”
According to the ATF, firearms lost or stolen from dealers jumped 25% in 2016. Reports of guns stolen or lost by civilians went up 42% between 2005 and 2014.
Such increases may make a reality out of, Park- Pettiford's prediction, that more families will suffer his pain.
According to the FBI, of the estimated 2 million guns lost or stolen in the U.S. in the last 10 years, a quarter were not reported to police.
As the series Missing Pieces: Tracing Stolen Guns in America continues, NBC 7 Investigates talks to a local law enforcement officer whose gun was stolen. He has a remarkable story of its recovery and a more important message about the responsibility of gun ownership. That story airs 6 pm Tuesday on NBC 7.