Superintendent Jason Murphy, who is leading the investigation into McClean's killing, said he believed many of the answers to solving the murder belong in the north Belfast community where the ambush took place.
McClean, who had links to dissident republican group ONH (Oglaigh na hEireann) and previously served in the British Army, was gunned down on the Cliftonville Road on Tuesday evening.
Police spent hours combing the area for evidence on Wednesday.
Superintendent Murphy described the shooting as "callous" and said his thoughts were with the victim's family.
He revealed that when the murder took place McClean was in the driver’s seat of a red Audi Q2, which was parked in the driveway of a property.
The 54-year-old was then approached by a single gunman and shot a number of times.
Superintendent Murphy said police had established the lone gunman crossed from Clifton Crescent into the Cliftonville Road and fired a number of shots at close range.
The gunman was wearing dark clothing and gloves and after the shooting walked back towards Clifton Crescent.
Superintendent Murphy said it was a "brutal and calculated murder carried out by someone who has no regard for life".
"There can be no justification for it whatsoever. It was carried out in a built up residential area, putting families living there at risk and it is extremely fortunate that no-one else was injured as a result of this shooting," he said.
"I have no doubt that local people will have been left extremely traumatised by this ruthless murder."
He called for anyone with information to share it with police.
"I am directly appealing to the local community and those who were in the area last night to help us," Superintendent Murphy said.
"I would also like to see any CCTV footage, captured by local residents or businesses and dash-cam footage.
"Do you know who may have been involved in Danny’s murder?
"Did you see Danny McClean or a red Audi Q2 in and around the Cliftonville Road area or adjoining streets between 7.30pm and 8.30pm last night?
"Do you know anything about Danny’s movements on Tuesday 2nd February?
"Were you in the area of the Cliftonville Road or Clifton Crescent yesterday, between 7.30pm and 8.30pm? What or who did you see?"
First Minister Arlene Foster described the shooting as terrible news for people in the area and expressed her sympathies with the family of the man who died.
Deputy First Minister Michelle O'Neill said the murder was "not something that is acceptable at any level in our society and I think that anyone with information should come forward to the PSNI and assist with the investigation".
Superintendent Murphy asked anyone with information "no matter how insignificant it may seem to contact detectives on 101, quoting reference 1593 02/02/21, or use the MIPP portal at https://mipp.police.uk/operation/PSNI21Q02-PO1.
You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/.