A 21-year-old man who allegedly raped and murdered a mentally challenged girl was arrested from a hideout in Khoken village, according to a Manipur police report. A special team of the Manipur Police arrested the alleged accused, namely, Kammalsawm Singson, 21, a resident of Songsang village in the Thanlon subdivision of Pherzawl District. FIR has been registered in this case.