Instead, Alex Dragaytsev, 45, was cited Tuesday for failure to use caution for hazardous conditions — a charge that carries a $60 fine.
The resident of Montreal-area Longueuil was released from custody, said Albany County prosecuting attorney Peggy Trent.
"We did not feel that there was, from the investigation that was completed at this point, that we could proceed with the charge at this point," Trent said.
Trent said she didn't know where Dragaytsev went after he was released.
Earlier on Tuesday, Wyoming Highway Patrol Sgt. David Wagener said Dragaytsev was being held at the Albany County jail in Laramie.
The pileup began after two commercial trucks collided, causing one to jackknife in both westbound lanes, Wagener said.
The pileup happened around 8 a.m. Monday about 30 kilometres west of Laramie in dense fog and light slush. More than 60 vehicles were involved and traffic was shut down for about 160 kilometres in both directions as the fiery crash sent up a column of thick black smoke.
The Wyoming Highway Patrol identified the two motorists killed as Lynn Freeman, 58, of Williford, Ark., and Jenay L. Breden, 23, of Westminster, Colo.
Dozens of other vehicles piled into the crash on Interstate 80. The 64 vehicles involved included a tanker containing a flammable liquid that caught fire and required foam to put it out.
It appeared no hazardous materials leaked, said Bruce Burrows, spokesman for the Wyoming Department of Transportation.
An estimated 20 to 25 people were taken to a nearby hospital — three were admitted and one was transferred to a hospital in Denver.
The crash occurred four days after several pileups during a blinding snowstorm closed the busy interstate for two days.
In both cases, poor visibility was a factor. However, authorities were still investigating and could not say whether the latest wreck involved motorists travelling too fast for the conditions, as occurred in last week's crashes.
Wagener said many details of the case will be part of the final police report into the crash, which is days, if not weeks, away from being completed.
— with files from Sidhartha Banerjee of The Canadian Press in Montreal