BURLINGTON, Ont. -- Halton Region police hope the discovery of a wallet in a field can help lead them to a 79-year-old Burlington, Ont., woman who's been missing since July 5, 2016.

Helen Robertson, who has Alzheimer's and is known to go on long walks, was last seen at her residence (on Millcroft Park Drive).

On Monday, Burlington city workers found a brown leather wallet believed to belong to Robertson inside a fenced-in field in a city park.

Police believe the wallet was left there between last Friday and Monday after being found at some other location.

Helen Robertson wallet

Police are appealing for the person who found it to tell them where it was found so they can conduct a further ground search for the elderly woman.

Robertson is white, five-foot-two and 110 lbs with white collar length hair. She was believed to be wearing a red, long sleeved collared shirt and two different shoes at the time of her disappearance.