A homicide investigation into the mysterious death of an Edmonton nurse found dead in a burning car last week now centers on a white van.

Police released photos of a 1990 Dodge Ram full-size white van Tuesday, asking the public to come forward if they saw the vehicle in west Edmonton March 12 or March 13.

"Officers seized a white van over the weekend and they were able to do some forensic testing on it and they released that van back to a person of interest in the latest homicide," police spokeswoman Karen Carlson said.

Investigators said Shernell Sharon Pierre was shot to death before her body was left in a burning car. They also released a basic description of the suspect, possibly a black man in dark clothing, who was in her car briefly Wednesday night.

Police are asking neighbours around 170 Street and 87 Avenue to search their yards and alleys in case the gun was discarded.

Late last week, police said the licensed practical nurse left work through the Misericordia Hospital's main doors at around 11 p.m. on Wednesday night. About a half an hour later her car was found engulfed in flames.

Investigators believe there was someone else in the car with her and they say that person fled the scene.

Police also found a purse on a busy walkway on 176 St. and 87 Ave on Thursday afternoon, which they now believe belonged to Pierre. Investigators said the killer likely dropped the purse in the path.

"At this point it's not believed to be a random act and now officers are tasked with trying to determine exactly what happened between the time that the victim had left her work and the time that the vehicle was found on fire," said Edmonton Police Service spokesperson Karen Carlson.