PALM BAY, Fla. -- Police searched the streets, combed the city and area canals from a helicopter, and talked with her friends and family.

But a week after 85-year-old Frances J. Sentner stepped into her car and rode off, detectives still are struggling to find even one clue that might lead to the missing woman's whereabouts.

"Our position is that we're going to aggressively search for her until we find her," Palm Bay police Detective Mark Mynheir told Local 6 News partner Florida Today. "I don't see any evidence of foul play. We think she's simply missing. We've put out the intelligence bulletins and are in contact with the hospitals."

Palm Bay police issued a "Silver Alert" -- a special public bulletin for missing and endangered elderly adults -- within hours after Sentner's daughter reported her missing. The 85-year-old woman was driving a gray 1991 Oldsmobile station wagon with a tag number of X90 VGX.

The alert also was featured for six hours on lighted traffic signs along Interstate 95, while Mynheir got into his vehicle and followed several possible paths Sentner could have followed to the Meals on Wheels agency in Melbourne where Sentner reported that she was going.

"She's had a number of memory issues, and they've gotten considerably worse than before. She stopped paying bills and would begin losing her keys," said her daughter, Kathleen Sentner.

Kathleen Sentner, who moved in with her mother in February, said her mother was set to be evaluated, and had gotten lost while driving in the past.

Frances Sentner also volunteered with Meals on Wheels, and helped serve communion to the sick and shut-in members of her church.

Before heading to the car, Frances Sentner told her daughter, "I love you," and indicated she would return, Kathleen Sentner said.

There have been several reports of sightings, but none have provided any solid leads, investigators said.

In recent weeks, the mother of five adult children also began talking more about the fifth anniversary of the death of her husband, George. Her husband is buried in New Jersey.

"She mentioned going to New Jersey to visit my dad's grave. But she doesn't have any money. There's been no bank activity, and she didn't take her medication," Kathleen Sentner said.

"Everybody's missing her. Everybody loves her."