Noah Donohoe disappeared in North Belfast in June, sparking a huge search effort.
His body was later found in a storm drain.
The 14-year-old’s mother, Fiona, has launched a public appeal to find out what happened to her son.
She has set up dedicated pages on Twitter and Facebook, called MyNoah Donohoe, as she seeks answers about his disappearance and death.
On Tuesday, Belfast City Council announced City Hall will be lit up in blue this weekend to back the campaign.
The Mayor of Derry City and Strabane District, Brian Tierney, has now also pledged his support.
The Tinnies sculpture in Strabane, Ms Donohoe’s home town, will be lit up blue on Saturday and Sunday.
Mr Tierney said: “This is every parent’s worst nightmare and the fact that Noah’s family are left with so many unanswered questions just adds to the sadness of this terrible tragedy.”
“By lighting the Tinnies up blue for ‘Remembering Noah’ this weekend in his mum Fiona’s home town of Strabane, we will show the family that we stand firmly with them in their quest for truth and raise awareness of their campaign.
“I would like everyone to think of Fiona and the Donohoe family this weekend, and I want to personally stress my own support for them as they seek the answers they need to give them some comfort following Noah’s tragic death, and to move forwards in the knowledge that everything has been done to find out what happened to him in his final hours.”
