The Utah Department of Public Safety, or DPS, arrested two men on Wednesday for allegedly firing their guns at a vehicle in 2009 and killing one of the occupants, according to officials.

The DPS State Bureau of Investigation said in a press release on Thursday that Nicholas Dean MacNeil and Aaron J. Paul Campbell were arrested after a 14-year investigation that included interviews and help from the public.

NIcholas MacNeil Mugshot

Utah DPS investigators arrested Nicholas MacNeil, pictured, and Aaron J. Paul, both known members of the Norteños gang, for allegedly shooting and killing a man on I-15 in 2009. (Salt Lake County Sheriff's Office)

The two men are accused of firing shots at a green Jeep Cherokee occupied by two men thought to be rival gang members on January 9, 2015, on Interstate 15.

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The shots killed one of the brothers inside the Jeep, the press release read.

MacNeil and Campbell are associates of the Norteños gang, and both have violent criminal pasts.

(iStock)

But because of MacNeil's and Campbell’s violent pasts, the release noted, the safety of witnesses who led to their arrests is a primary concern for investigators and prosecutors.

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Requests for more information about the case were not immediately provide.

When requesting mugshots of both suspects, the Salt Lake County Sheriff’s Office said photos would only be provided after suspects are convicted of crimes.

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MacNeil was convicted of aggravated assault in 2015, and a mugshot was provided. Campbell did not have any prior convictions on the books in Salt Lake County, according to county personnel.