Beth Davis initially tried to alert employees to the incident by shouting "there's a naked man in the bathroom masturbating" for several minutes.
When that failed, and with the man heading for the door, Davis whipped out her cellphone and started shooting video of the man as he sauntered away.
Despite her attempts to detain him, an employee, following the store's protocol, allowed the man to leave.
But Davis continued to follow the perp as he got in his car and sped away.
Photos she took of the car's license plate eventually led Tulsa sex crimes detectives to the Broken Arrow home of 37-year-old Brian Hounslow.
Hounslow was subsequently arrested and charged with indecent exposure. His bond was set at $5,000.
"Who gets up at 8:30 in the morning and decides they're going to go to Walmart, take off all their clothes and masturbate in the women's bathroom?" Davis rhetorically asked KJRH. "It's pretty sick ... How could you think you weren't going to get caught?"