Heartbreak as student may have been killed by long-term use of nitrous oxide laughing gas; Ellen Mercer, who died in hospital the day after having a 'sudden and unexpected cardio respiratory collapse', had taken a form of nitrous oxide, which was not an illegal drug at the time

Byline: By, Bradley Jolly A student may have been killed by the long-term use of laughing gas, an inquest heard. Ellen Mercer, 24, suffered a 'sudden and unexpected cardio respiratory [...]