The Knox County sheriff announced on Monday that a special tip line was established for information about three people who have been missing since last week.
Sheriff David Barber said that authorities want to remain optimistic that Tina Herrmann, 32; her son, Kody, 11; and a friend, Stephanie Sprang, 41, are alive.
Barber added that "there is a possibility" that the three were killed.
His comments were made one day after a 13-year-old girl who was also missing was found alive, bound and gagged in the basement of a Mount Vernon home.
Matthew Hoffman, 30, was arrested and charged with Sarah Maynard's kidnapping. The 13-year-old was removed from Hoffman's home after authorities swarmed the location on Sunday morning.
Barber said that Sarah Maynard was released from a hospital and was at home with family members, 10TV's Tanisha Mallett reported.
He said the girl is helping investigators, but would not say whether Hoffman was cooperating.
"Not only is she assisting the investigation, under the circumstances a 13-year-old girl being held captive for four days by a total stranger, I would call her the epitome of bravery ," Barber said.
Investigators tracked Hoffman down with the help of a receipt for a tarp that was purchased at a Walmart store in Mount Vernon, 10TV News reported.
Investigators were reviewing surveillance footage from inside the store, 10TV's Maureen Kocot reported.
Investigators said a deputy noticed a man sitting in a silver Toyota on Thursday night in a parking lot near where Herrmann's pickup was found on the campus of Kenyon College.
That man told investigators his name was Matthew Hoffman, but at the time deputies had no reason to arrest him, Kocot reported.
"If somebody's sitting in a vehicle, whether it's a couple of kids necking or whether it's somebody sitting there, they're going to inquire what they're doing, run the license number, things like that," Barber said.
Investigators said they have no reason to believe Hoffman had an accomplice.
Crime scene investigators removed bags of evidence from nearby Foundation Park on Monday, located near Hoffman's home.
Divers pulled two cars from a pond at Foundation Park, but investigators later determined they
were not likely related to the case, 10TV's Glenn McEntyre reported.
At least one of the cars appeared to be stolen, police said.
Police apparently found items in the park and gathered evidence that filled a two-foot bag, 10TV News reported.
No one has seen or heard from the missing women or children since Wednesday, when Herrmann failed to show up for work. On Thursday, both of her children were absent from school.
Investigators did not elaborate over the weekend about the information that led them to Hoffman's home on Columbus Road, but his parents have a house on Apple Valley Drive in nearby Howard, Ohio, the same street where the Maynard children disappeared with Herrmann and Sprang, 10TV News reported.
Barber said that special attention was being paid to blood that was found inside Herrmann's home. Barber called the amount of blood "unusual."
"It is obvious that someone was injured in the house," Barber said.
Kody A. Maynard is 4 feet, 10 inches tall, weighing 70 pounds, with brown hair and hazel eyes.
Sprang is 5 feet, 3 inches tall, weighing 110 pounds, with blonde hair and green eyes.
Herrmann is 5 feet, 6 inches tall, weighing 122 pounds, with sandy blonde hair and blue eyes.
The children attend East Knox Middle School in Howard, where counselors were on hand to help students.
Anyone with information about the case is asked to contact the Knox County Sheriff's Office at 740-397-3333 or the tip line at 888-363-8477.
Stay with 10TV News and refresh 10TV.com for continuing coverage.
November 15, 2010:
Police Block Off Park As Mount Vernon Search Continues
November 15, 2010: Suspected Kidnapper's Past Includes Arson Conviction
November 14, 2010: Missing Girl Found Safe; Man In Custody
November 13, 2010: Search For 4 Grows More Intense
November 13, 2010: Support Growing To Find Missing Family, Friend
November 12, 2010: Search Continues For Missing Women, Children
November 12, 2010: 4 Missing From Knox Co.; Discovery Of Pickup Prompts Kenyon College Lockdown