13 December 2012 Last updated at 07:13 ET

Sister of teenage Donegal suicide victim found dead

Friends of Erin Gallagher touch her hearse at her funeral in October

The sister of County Donegal schoolgirl Erin Gallagher, who took her own life amid claims she was bullied on the internet, has been found dead.

Shannon Gallagher, who was 15, died last night.

She was discovered in a house in Castlefin around midnight. Police say they are treating her death as a personal tragedy.

Staff and pupils at the Finn Valley college where she was a pupil were told the news this morning.

Her death comes less than two months after her 13-year-old sister Erin died.

She took her own life after allegedly being bullied online.

She was also a pupil at Finn Valley College.

In a statement the body that runs the school said its thoughts and prayers were with Shannon's family at this sad time.

It added this is an extremely difficult time for all concerned.

A critical incident team is in place in the school as a support for students and staff.