Cold case detectives in the US have launched a new investigation into the brutal murder of a Scottish nurse at a US religious college 30 years ago.Elizabeth Mackintosh, 50, was found beaten, strangled with a cord and stabbed in the neck in the toilet of a chapel at the Covenant Theological Seminary in Creve Coeur, Missouri, in March 1990.Elizabeth, the daughter of a former Moderator of the Free Church of Scotland, was originally from Edinburgh and was studying at the seminary for a degree in