More than 30 police officers stopped early morning commuters exactly one week on from the murder of Brian Harkins, in Rutherglen, South Lanarkshire.
Police revealed they had narrowed down the key period when the gunman struck, and are focusing on a time frame of between 7am and 9am last Wednesday.
Mr Harkins is understood to have been shot around 8am just yards from the busy main road. The roadblock was set up in Westmuir Place, close to the 45-year-old's home.
Mr Harkins, who was known to police, was found dead by a family friend around 10am last Wednesday, but senior detectives believe the killer struck earlier that morning.
He was pronounced dead at the scene, which sits close to Prospecthill Road, a busy thoroughfare which joins Rutherglen and Toryglen.
Police officers stopped cars, buses and passers-by this morning and quizzed them on the movements last week to gain information on who was in the area at the time.
Officers boarded buses and spoke to passengers who may have been passing by last Wednesday. Vehicles were stopped on both sides of the road and traffic was tailed back along Westmuir Place.
Detective Chief Inspector Kenny Graham, who is leading the investigation, said: "We are focusing on a critical period of time between 7am and 9am. Someone must have seen the gunman approach and leave the house and we are keen to speak to anyone who was travelling along Westmuir Place around that time last Wednesday.
"I would like to thank the public for their help today. This was not a random attack, and we also wanted to reassure the public with our high visibility presence this morning. There have also been extra patrols in the area."
DCI Graham said he believes someone holds vital information about last week's incidents.
He added: "It is a busy commuter road leading to Prospecthill Road. People would have been heading to work and taking their children to school and they may have seen something which could be vital to our investigation. Did they see someone coming and going from the house, was there a car parked nearby?"
Floral tributes have been placed outside Mr Harkins' home. A heart-shaped arrangement was placed alongside flowers spelling out Brian.
DCI Graham said: "The family are understandably devastated and are keen to see a quick resolution to this investigation."
Anyone with any information is asked to call 0141 532 5415.