Suspect in Robbery and Assault of Security Guard Turns Himself In to Police

The main suspect in the brutal assault and robbery of an apartment complex security guard in Annandale has turned himself in to police.

Fairfax County police said that 20-year-old Tin Thien Diep, who lives in Falls Church but frequents the areas of Annandale and Burke, turned himself in to authorities on Tuesday.

Diep is accused of causing serious injuries to a security guard and stealing his phone on May 21, along with the help of three friends.

Police said the 30-year-old guard, who remains unidentified, was conducting regular patrols around the apartment complex where he works, located in the 8300 block of Tobin Road in Annandale, when he saw a figure, later identified as Diep, slumped over the steering wheel inside his car.

The guard approached the vehicle to check on the person's well-being when Diep awoke and became agitated with the guard. At that point, three of Diep's friends approached from nearby and also started arguing with the guard.

One of the suspects allegedly assaulted the victim, then fled with the other suspects in the vehicle, according to police. Further investigation revealed the vehicle circled back around and Diep allegedly assaulted the victim again, then fled the area in the car again. The victim’s phone was stolen during one of the assaults, police said.

The victim was transported to the hospital with serious, but non-life-threatening injuries.

Diep is charged with robbery and malicious wounding.