Read more: Celtic FC boss and high profile supporters sent nail bombs in the post
There's been a break in the case of the bomb threats made against Celtic manager Neil Lennon.
Police in Scotland are this week attempting to locate a couple in connection with their investigation.
The couple, who are believed to be in their 20's, were reportedly seen in the Ayrshire town of Kilwinning on the same day the most recent bomb threat was discovered there.
In total Scottish police have intercepted four parcel bombs, two of which were addressed to the lawyer Paul McBride and former Scottish politician Trish Godman — both prominent Celtic fans.
Police investigating the incidents now believe that a former soldier may be linked to the bomb packages, which contained liquid explosives and nails.
A close forensic examination of the four parcels demonstrated that the person who made them had extensive knowledge of explosives.
"These devices are viable and well-constructed," a source told the Belfast Telegraph. "This terror campaign is being carried out by someone who knows what they are doing."