Pierce County Prosecutor Mark Lindquist says 48-year-old Anderson Hamilton of Puyallup was under the influence of drugs at the time of the head-on collision on Highway 167 east of Tacoma.
The crash killed 34-year-old Shanna Huttenstine of Tacoma. Her fiance and the taxi driver were injured -- the taxi driver still in critical condition at St. Joseph's Hospital.
Huttenstine's fiancee, Jason Spree, who was sitting next to her says she was 12-weeks pregnant and that the baby also died. According to state law, since the baby would not have survived outside the uterus on its own, prosecutors cannot file a second homicide charge.
A preliminary investigation found that the pickup was heading north on Highway 167, also known as River Road East, when it crossed into the southbound lane as the taxi was approaching from the opposite direction.
The taxi driver swerved to avoid the pickup but was struck on the front driver's side in a glancing head-on crash.
Police found injection needles and what appeared to be marijuana in the truck driver's pockets. He refused a field sobriety test, but troopers said he appeared to be under the influence of drugs.
Investigators are still awaiting toxicology reports from Hamilton, however Pierce County Prosecutor, Mark Lindquist, says he's convinced Hamilton was driving impaired.
"This is another unfortunate example of why drugs and driving don't mix," said Lindquist. "He exhibited a lot of the signs of being under the influence. There was no alcohol in his system and so it's a reasonable inference that this was due to drugs."
Troopers claim the suspect's wife told them they recently moved to Washington and that Hamilton was excited because marijuana was legal.
Hamilton is being held on $500,000 bail.