Murderer handed victim mystery envelope.
Alistair Wilson, aged 30, was gunned down in Nairn, near Inverness on Sunday night after he put his two children to bed.
Northern Constabulary is still trying to establish a motive for the killing.
But the officer leading the investigation revealed Mr Wilson took an envelope from the gunman and left the door to speak to his wife. Police refused to disclose details of the conversation but when Mr Wilson returned to the door he was shot three times with what is thought to be a small automatic handgun.
The killer ran off from Crescent Road towards the Links area of Nairn.
The envelope, which is not thought to have been opened, has not been recovered.
Detective Chief Inspector Peter MacPhee said: 'We now have information that there was an envelope which was seen and which Alistair took possession of, it was a blue or green envelope.
'I can tell you we have not recovered it but Veronica saw Alistair in possession of the letter.
'Alistair went back into the house for a short time, he came back in with the letter.
'There was a conversation between Veronica and Alistair, he went back out then there were three bangs and she found him injured on the doorstep.'
Mr MacPhee added: 'I still have not established a motive and I do not know why Alistair was killed, but there is a murderer out there.
'There is still some concern within the community after what is an extremely rare crime, and we are responding to it as well as we can.'
Detectives have ruled out mistaken identity.
Detective Superintendent Gordon Urquhart said: 'We are going to be taking Mr Wilson's life to bits, to be honest, and looking at his background and his work.'
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