From Longman Dictionary of Contemporary Englishstring somebody ↔ up phrasal verb informalKILLto kill someone by hanging them → strung-up → string→ See Verb table
Examples from the Corpus
string up• He had hung himself, just strung himself up.• I would love to string them up.• Oh, I wished I still had even my scorpion on a string to run up and down somebody's back!• No-one ever explained how Kleine, who was too drunk to walk, managed to string himself up early the following morning.• Giffin, weird six string pick up guitar, £250.• She holds a string of words up to them like a caption.• I fasten it with the string I rigged up when the latch broke. 