( CNN ) -- Tuesday was the first day of classes at the Portland , Oregon , school where Kyron Horman allegedly was last seen in early June . The new year at Skyline Elementary also brings 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 the missing 7-year-old boy were moved Tuesday 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 criminal investigation into Kyron 's disappearance has now entered its fourth month with no signs of the child . Police searches are ongoing as officials ask the public for tips and leads on his whereabouts . Kyron 's stepmother , Terri Horman , who said she dropped him off at school on the morning of June 4 , 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 disappearance of my son Kyron . '' Court documents also allege Terri Horman attempted to hire a man to kill her husband . Investigators are seeking anyone who may have seen a white pickup truck believed to have been driven by Terri Horman on the morning Kyron vanished . Thursday will mark Kyron 's eighth birthday . Desiree Young , his biological mother , said she will celebrate the birthday by releasing red balloons outside a church in Medford , Oregon .
Video cameras are being put in place at Skyline Elementary in Portland . The school district is also installing a new security system that will be able to monitor the entire school. Kyron Horman 's father has said he thinks his now-ex-wife was involved .