LAFAYETTE -- The reason for a blood spatter discovered on an ATM over the weekend remains a mystery, but investigators have ruled out foul play in the sanguine deposit, police said.

Surveillance video pulled from the front of the Wells Fargo branch in the 3600 block of Mt. Diablo Boulevard shows an unidentifiable man shaking out his hand about 1:30 a.m. Sunday, said Chief Michael Hubbard.

Later that morning, blood found on an ATM at the bank sparked speculation of violence as police confirmed the blood was human but could not immediately determine how it got there. Everything from gunfire to stabbing was quickly ruled out because of the absence of any police calls or hospitals reporting corresponding injuries, but the rumors persisted.

Hubbard said it was not possible to tell whether the unidentified man was bleeding or flinging blood he had brought there -- he was standing as much as 10 feet away from the security camera.

Anyone with information can call police at 925-284-5010.

Robert Salonga covers public safety. Reach at him at 925-943-8013. Follow him at Twitter.com/robertsalonga.