( CNN ) -- Four months after a criminal investigation began into the disappearance of an Oregon boy , officials continue to ask the public for leads and tips . Thursday marks Kyron Horman 's 8th birthday . Desiree Young , Kyron 's biological mother , said she will celebrate the birthday by releasing red balloons outside a church in Medford , Oregon . His stepmother , Terri Horman , said she dropped him off at Skyline Elementary School on the morning of June 4 . She has been the subject of intense scrutiny for several months . In divorce filings , her ex-husband , Kaine Horman , said he believes that Terri Horman `` is involved '' in the boy 's disappearance . Court documents also allege Terri Horman attempted to hire a man to kill her husband . Meanwhile , Skyline Elementary began its first day of classes for the year on Tuesday with additional security measures to protect the children and staff . In a letter to parents , Principal Ben Keefer said video cameras will be installed this weekend at Skyline . `` These cameras will show external views of the building as well as the main hallway , '' he wrote . Also , security procedures will be reviewed to ensure they are effective , he added . Tributes , messages , posters and cards that adorned a `` Wall of Hope '' for Kyron were moved from school property to a fence outside a nearby fire station , said the Multnomah County Sheriff 's Office . `` We 're happy that the fire district can provide this service to the community , '' said Tualatin Valley Fire & Rescue Communications Officer Brian Barker . `` Our hearts go out to Kyron 's family and we all hope for a positive resolution to this case . ''
The investigation into Kyron 's disappearance continues . His mother says she will release balloons to celebrate his birthday . Video cameras are being put in place at Skyline Elementary .