A father of two has been stabbed to death in front of his children, police have said.
Police believe a robbery was the motive for the attack, and that Mr Nicol was targeted because the killer mistakenly thought there was a large sum of money in the flat.
Officers are now asking people to come forward with any information about the attack, which happened at about 9.05pm on Thursday evening.
Detective chief inspector Martin Fergus said: “For whatever the reason, to carry out such a brutal attack in front of such young children is absolutely sickening. It shows an absolute disregard for their safety or suffering. This callous killer must be caught.
“Although our murder investigation is progressing, we have been disappointed by the public response to our previous appeal.
“I believe that the answer to this murder lies in the local community and I am in no doubt that there are people out there who have vital information on this incident, who have not yet come forward. I would urge them to look to their conscience and contact us.”
The suspect is described as white, between 20 and 30 years old, and about 5ft9in. He was of slim build, with an unkempt, reddish brown beard and moustache.
He is said to have had bad teeth, with some missing, and spoke with a local accent. He was wearing a black beanie hat, with a logo which may have been Timberland, a black top, and black jeans or trousers or jogging bottoms.