CAPE TOWN – Western Cape police have made a breakthrough in the murder of grade 10 pupil Deveney Nel.A 17-year-old suspect has been arrested after an extensive investigation.Nel (16) was found dead in a storeroom at Overberg High School in Caledon in August.She had been reported missing by her mother after she did not return home from school.Western Cape Education MEC, David Maynier, says the incident has dealt a great blow to the school and support to pupils and staff will be provided.