The man who cops say they arrested at the UnitedHealthcare campus in Minnesota has just been identified … and only TMZ has his mug shot.

Law enforcement tells us Ian Stanley Wagner was busted Monday outside UnitedHealthcare HQ and he’s been booked for allegedly making threats of violence.

The FBI and Minnetonka Police say Wagner contacted the FBI Minneapolis Field Office on Monday morning and “issued threats of violence directed at the United Healthcare facility if specific demands were not met.”

The feds add … “There is currently no indication that the individual had specific grievances against United Healthcare.” That’s notable because earlier this year UnitedHealthcare CEO Brian Thompson was shot dead in New York City, with prosecutors claiming Luigi Mangione pulled the trigger.

The FBI says a crisis negotiator talked to Wagner over the phone … and FBI Task Force Officers working with Minnetonka Police helped take him into custody after he surrendered.

As we reported … the guy claimed he had a gun, demanded $1 million and said he wouldn’t be taken alive. Cops say they recovered a firearm from his car.