EDMONTON — Alberta RCMP say they are trying to locate six potential witnesses in their investigation into the $700-million wildfire last May that ravaged Slave Lake.

The province said in November that an unknown arsonist ignited the raging forest fire that reduced a third of the town to ash and left 2,000 people homeless.

The government's Sustainable Resource Development Department then handed the file to the RCMP, which said it would be difficult to investigative more than five months after the blaze.

Doris Stapleton, an RCMP spokeswoman, said police are still trying to gather evidence and have yet to determine if the probe is a criminal investigation.

"We are using the SRD report that suggests it was arson to try and collect information to try and see if it supports a criminal investigation of arson," Stapleton said Wednesday.

"We are trying to determine if it is and it is really important to speak with these people, because that will help us."

Mounties say these six people were seen in the area where the fire broke out on May 14, the day before it burned the town.

Stapleton said these people are not criminal suspects, but potential witnesses. They include:

-- Two men who were seen driving ATVs 15 kilometres east of Slave Lake on the north side of Highway 2.

-- The driver of a green Dodge Neon parked closer to town on the side of Highway 2 who was seen near the treeline.

-- Anyone associated with a Ford pickup truck that was seen near the Flat Top Observation tower.

-- Two people who flagged down firefighters and directed them to burning brush east of a weigh scale on Highway 2.

People with any information are being asked to phone RCMP or Crime Stoppers.

The blaze destroyed 400 homes, the community's new government building, the library, as well as two churches and the radio station.

The town, 250 kilometres northwest of Edmonton, is still rebuilding.

Last November, Frank Oberle, minister of sustainable resources, said investigators in his department had ruled out all other possible causes for the fire. His department said there was enough forensic evidence for an arson investigation, but declined to provide any details.

A review commissioned by the province into how the fire was fought and the effectiveness of fire management programs was expected to be complete last fall but has not been made public. It was led by Bill Sweeney, a one-time RCMP senior deputy commissioner.

The review did not deal with how well the evacuation of the town was carried out during the fire.

Residents have been asking why they were not given ample warning to leave. Some who left on their own were forced to turn around when roads were closed.

Municipalities are responsible for ordering evacuations but are dependent on information and fire updates from the province.