Nicola Sturgeon said the authorities cannot be sure there are no other Scots affected.
6 Month Anniversary Of Gran's Murder
Glasgow grandmother Jean Campbell was killed within sight of her home in Glasgow's Cranhill in December last year.
Over the last 6 months, officers have taken over 1,500 DNA samples, and conducted house to house enquiries, but the case remains unsolved.
Despite several public appeals and a reconstruction on BBC Crimewatch they still need anyone with information to get in touch.
DCI Colin Carey, the officer in charge of the investigation says: ''I would like to reassure Jean's family and friends and the community of Cranhill that this is still very much a live investigation with a team of dedicated officers working on the case.
''Although six months have passed I remain confident that we will find out what happened to Jean and the motive behind her murder. We still need the public to help us. I would ask anyone who was in or around Cranhill Park on Friday 13th December and has not yet spoken to police to contact the incident room as soon as possible. As I have said before, please do not assume that we know what you know or that someone else will have given us the information you have.
"I would also remind anyone with any information that Crimestoppers have offered a reward of up to £5000 for information.''
He continues: ''Jean's family are devastated by the loss of their wife, mother and grandmother and they deserve answers. Anyone with any information is asked to contact the incident room or Crimestoppers.''
Family members say Laura Macintyre and Eilidh MacLeod haven't been heard from since the explosion.
The families of two girls from the Western Isles missing after attending the concert in Manchester targeted in a terror attack have issued appeals on social media.
Crews were called to the former Royal Victoria Hospital site this afternoon.
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