Police today arrested a robbery suspect less than 20 minutes after a heist at a Spokane Valley convenience store. Matthew J. Horpel, 23, was seen running northbound at Valleyway and Blake when officers arrived just after the 1 p.m. robbery at McDonald Food Mart, 13105 E. Sprague Ave., according to police An employee said the robber implied he had a gun but did not display one, then left with cash. Police say Horpel was not armed when they arrested him at gunpoint 17 minutes after the robbery. Horpel’s criminal history contains primarily traffic offenses, police said.