"The family would like to thank all the emergency services and agencies who are involved in the search for Grant, particularly Surrey Police, for their dedicated help."
She added: "We would now ask that our privacy is respected at this difficult time.”
Surrey Police is continuing the search in and along the River Wey near the Guildford Borough Council offices.
Searches of the river have continued today, with police officers working alongside colleagues from Surrey Fire and Rescue and Surrey Search and Rescue.