Mother of Ronan Kerr: 'Don't let his death be in vain'

The mother of a murdered Northern Ireland police officer has paid tribute to her "wonderful" son.

Constable Ronan Kerr, 25, died after a device exploded under his car outside his home in Omagh on Saturday.

Nuala Kerr said her son "loved his work" and "had all the attributes of a great police officer".

She also urged people to come forward with information saying "someone knows something".