Land searches for the missing Co Tyrone youth, Brendan Rushe, have been scaled down as efforts were yesterday concentrated on the shoreline close to Donegal town.
Gardaí said the next three days would be crucial, as the tide reaches its lowest point on Thursday when the bay practically empties.
A number of items were found yesterday along the shoreline, including a pair of black shoes. The Rushe family did not believe the shoes were Brendan's, but a Garda spokesman said they would be sent to Dublin for forensic examination.
About 200 civilians joined gardaí in the search yesterday, backed up by dog units, and divers continued to search Donegal Bay. The Garda sub-aqua unit was called away to another incident but is expected back in Donegal today.
Sgt Ignatius Larkin said the search would be maintained at current levels until at least Thursday. He said he believed inland areas had been searched as thoroughly as possible. Land within a three- to four-mile radius of the town as well as all roads out of the town had been combed.
Checkpoints were mounted around Donegal town in the early hours yesterday, exactly one week after the 15-year-old schoolboy was last seen.
Questionnaires were distributed on Sunday night as people entered the disco Brendan attended the previous week.
Sgt Larkin said gardaí had received hundreds of calls of possible sightings, and all were being checked out. He repeated his appeal for farmers to check land and outhouses and for property-owners in the town to search premises.