MINNEAPOLIS — A 20-year-old man who showed up at a Minneapolis homeowner’s door “frantic, paranoid” and pleading for help was charged Monday with fatally shooting the homeowner who was trying to assist him.

Devon Parker of Minneapolis was charged in Hennepin County with one count of second-degree intentional murder in the death of Thomas Sonnenberg, a 69-year-old retired technician who was killed with his own gun in his home shortly before noon Friday.