Franklin police said they were focusing their search on watery areas and using dogs on Thursday as they continued to look for Michael Doherty, the Duke University student who disappeared while walking in his hometown early Sunday.

Franklin Deputy Police Chief James A. Mill said during a morning news conference that the search area has a radius of a mile. Police have previously said it spans a marshy stretch along the border between Franklin and Bellingham.

As the search entered its fifth day, Mill said rescuers would be looking in harder-to-reach places.

“They’ve been very difficult to get into, so we’re trying to hit those areas hard today with the canines,’’ he said.

Police have said they do not suspect foul play in the disappearance of the 20-year-old Doherty, who was last seen around 1:30 a.m. Sunday as he left a party on Phyllis Lane, planning to walk in the rain to the family’s home on Catherine Avenue about a mile away.

His parents said on Wednesday that they are holding out hope that he could be found alive.

“We want Michael here,’’ said his father, Dan Doherty. “We’re praying for a miracle.’’

Andy Rosen can be reached at andrew.rosen@globe.com. Follow him on Twitter at @andyrosen.