(Moorhead, MN)  --  An unusual police investigation involving tattoos and teenage girls in Moorhead.  Court documents say the man used a tattoo gun and foot pedal to apply the tattoos inside his Moorhead apartment.  A search warrant affidavit says the man goes by the name "Monster" and has a reputation for tattooing many students at Fargo South High School.  One girl told police she paid 23 dollars for a tattoo.  She said another victim was given free tattoos for bringing other girls to the man's apartment.  Police seized a cell phone, cameras, and tattoo supplies.  Charges have not been filed.