Three years after a 70-year-old woman disappeared from her fire tower lookout far out in the Alberta bush, police have no leads or suspects in the case.

Sgt. Patrick Webb with the RCMP said the investigation into the mysterious disappearance of Stephanie Stewart remains open.

"We do not have human remains, it's still considered suspicious and we are approaching it as a homicide investigation," he said.

Webb told CTV News that they have followed up on tips they've received, but none have led them to answer the question of where the woman is today.

And despite a $20,000 reward offered a year after Stewart vanished, police have not come across any tips within the last two months.

"We are still looking for public input," said Sgt. Patrick Webb with the RCMP. "This is certainly a wilderness area that people use. If people see anything out of the ordinary they should call police."

The cash reward was put up by the province and the Alberta Union of Provincial Employees. Stewart was an AUPE member.

"She just seems to have disappeared off the face of the earth," Doug Knight, president of the Alberta Union of Provincial Employees told CTV News Wednesday.

Back in August of 2006, Stewart was working alone as a fire spotter at a remote tower north of Hinton, near the Rocky Mountains. She was later reported missing after her supervisor hadn't heard from her by radio from the tower.

RCMP used more than 200 people and six aircraft to search 7,500 kilometres around the area. Investigators who searched Stewart's tower found that two pillows, a sheet, a Navajo-patterned quilt and a gold watch were all missing.

The woman, originally from Canmore, Alta., had worked at the same location each summer for 13 years.

Her daughter held a press conference following her disappearance pleading to the public to come forward with any information about her mother's whereabouts.

Stewart's daughter Lorie last heard from her mother the evening before she disappeared.

Police said they remain in very regular contact with the family to keep them involved as the investigation continues.

Webb said it's been very upsetting and "bewildering" to the family to have not heard from Stewart in three years.

There are over 100 fire-spotting towers in Alberta. About a year after Stewart's went missing, a provincial report was released recommending tougher security to better protect guardians in towers.

Duncan MacDonnell, spokesman for Sustainable Resource Development, which operates the towers,said the department is in the process of implementing security measures.

MacDonnell said by the end of this year, the majority of lookout towers will be fenced and gated. He said all lookouts are in regular radio contact during their shifts. Employees have specific call-in times, which they are in contact with a supervisor updating the status on weather or fire conditions in the area.

"Most of these towers are very isolated with no road access," said MacDonnell.

He said everybody within the department is aware of Stewart's case."We all remember Stephanie; we would all like to see some closure brought to this."

Police said anyone with information on the disappearance of Stephanie Stewart should call Crime Stoppers at 1-800-222-TIPS (8477) .

With files from the Canadian Press and news staff