Authorities say Trooper Searfoss has been placed on desk duty pending the outcome of the investigation.
The car fire that resulted from the crash was captured on video. It was obtained exclusively by Action News.
"As I got closer there was a lot of debris on the road and it was a large fire," Shavin Duffy of West Chester, Pa. said.
For Duffy, a musician with the band, Midnight Hour, the scene Friday night in Upper Dublin Township was absolutely chilling.
"I couldn't see, obviously, into the car, I was hoping the person had gotten out cause I did see someone standing in the left lane near the car, but I couldn't tell if someone was in the car," Duffy said.
Authorities say 21-year-old Robin Williams of the Logan section was killed after Barry Searfoss, an off-duty state trooper, rear-ended her 1997 Lincoln Town car with his 2003 Toyota Tacoma pickup truck.
He was taken into custody for suspicion of driving under the influence.
Action News spoke with Williams' devastated family late Tuesday.
"Her mom is very ill, bed-ridden, and her mom and her dad are severely devastated. They lost their baby; we lost the love of our lives. She had her whole life before her," cousin Doreen Thomas said.
"It's a great loss, a great loss. It's a shame, but our prayers go out for the family, and also for the trooper who was involved in the accident, I know his family is probably in turmoil as well," uncle Anthony McNeil said.
While authorities say the off-duty trooper has not been charged pending results of blood tests, Williams' relatives wanted to warn people in general about drinking and driving.
"People please take driving and drinking very seriously," McNeil said.
"Please, please I beg you. I lost my baby, I loved her and she loved her family," Thomas said.
The Montgomery County D.A.'s office is assisting in the investigation.
Authorities are asking anyone who may have information regarding the crash to contact the state police barracks at King of Prussia.
