Police are investigating a suspicious incident, near to the car park for Lidl at Charlotte Street, Carlisle, reported at about 7.30am on November 15.
It was reported that a blood-stained knife, along with a t-shirt and trainers were on the footpath near the car park.
A Cumbria Police spokesman said: “Upon forensic investigation, no blood was found on any of the items.
“Police are treating the incident as a possible offence of wasting police time.
“Officers are appealing for anyone with any information to contact PC 2531 on 101, referring to incident 38 of November 15.”
Alternatively, call Crimestoppers anonymously on 0800 555 111.