Here's more from The Phoenix New Times:
Police say Theriault had masturbated in front of the victim three times over the past three weeks, but the woman -- who was working to advertise a tax business -- didn't report the crimes at first. When she finally called the cops, a Tempe detective thought the guy's m.o. sounded familiar.
Back in 2008 and 2009, local residents had reported a man who appeared to be masturbating in public, says Tempe police Sergeant Steve Carbajal. Police ended up chatting with Theriault at the time and getting his ID, but no arrest was made. Going on the hunch, Tempe officers conducted surveillance of Theriaut's workplace on April 18. Sure enough, when Theriault got off work just after 5 p.m., he headed over to where the woman worked at the corner of McClintock and Elliot roads. He stepped out of his Jeep Liberty, pulled his pants down and began masturbating in the parking lot while watching the victim, Carbajal says.