Along the route, motorists pulled over and thousands of people watched respectfully from overpasses and sidewalks as the procession made its way to the ShoWare Center in Kent, where the service is being held.
The procession began at the Kitsap Mall in Silverdale at 7:30 a.m. with about 100 law enforcement vehicles, and made its way through Radulescu's hometown of Port Orchard to Joint Base Lewis-McChord, where Radulescu's son Erick is stationed.
Later, a larger procession of 700 vehicles left the base and headed for Kent, passing beneath crossed fire truck ladders with a large U.S. flag on their way to the 1 p.m. memorial service.
Leading the procession was a white hearse with Radulescu's casket, which was later carried in state inside the ShoWare Center.
As an honor guard kept guard over the casket, thousands of people filed inside the center to attend the memorial service. Law enforcement personnel came from as far away as Montana and Canada to show their support.
Before the service, Washington State Patrol Chief John R. Batiste said it is a "difficult day" for state troopers.
"As you can imagine, this is a very difficult day for the Washington State Patrol," he said. "In fact, this is a very difficult day for law enforcement in general across the state of Washington and ... it's a very difficult day for the citizens of this great state of ours. ... We've lost a real humble public servant."
Trooper Tony Radulescu
Radulescu, a 16-year State Patrol veteran, was shot Feb. 23 near the small Kitsap County town of Gorst by a driver who later took his own life. Six people have been charged with rendering criminal assistance.
Radulescu, 44, of Port Orchard was born in Romania and served in the Army during the Gulf War before joining the Washington State Patrol. His ability to speak Romanian, Spanish and Korean made him an unofficial translator for the county's law enforcement agencies.
Among those in attendance at his memorial service will be Gov. Chris Gregoire and Washington State Patrol Chief John R. Batiste.