A man arrested for allegedly stabbing a Greyhound passenger on Sunday was put on the bus in northwestern Ontario by police officers just hours before the attack, other passengers said Monday.

The bus remained parked beside a restaurant in White River while police interviewed passengers. (Marcus Grundt/Wawa News)David Wayne Roberts, 28, of Manitouwadge, Ont., is in police custody following a Sunday stabbing that sent a 20-year-old man to hospital in Sault Ste. Marie, Ont., with minor injuries. Roberts has been charged with aggravated assault and breach of probation and is scheduled to appear in a Sault Ste. Marie court Tuesday for a bail hearing.

Passengers on the Greyhound were bound for Winnipeg from Toronto said the attack took place about two hours after police officers put a man on the bus in Wawa, Ont.

Sgt. Larry Ross with the Wawa municipal police told CBC News that police had helped a man obtain a bus ticket earlier on Sunday, after an earlier encounter with police.

The man had been taken into custody early Sunday and charged with disturbing the peace, and was released later in the morning, Ross said.

Early Sunday afternoon, he returned to the police station and asked to go to a hospital "for psychological reasons," Ross said. Police officers took him to the hospital, where he was assessed by a doctor.

"The doctor on duty deemed there was insufficient grounds under the Mental Health Act to detain him, and [he] was subsequently released," Ross said.

At that time, Wawa police used social-assistance funds to purchase a bus ticket for the man to help him get to his home in Manitouwadge — roughly halfway between Thunder Bay and Sault Ste. Marie, Ross said.

"The subject had no transportation and a strong desire to go home, and the Wawa police addressed this need by obtaining a bus ticket via social assistance, which is a normal function for this police service for people who … find themselves transplanted with a lack of money or for whatever reason," Ross said.

The man was searched twice by Wawa police officers — once before he was put in a cell, and again before going to the hospital — and no weapons were found, Ross said. He was not searched before he got on the bus.

"We had no legal grounds to search him at that time," Ross said. "The police don't have the authority just to come up to someone and search them for no reason. There has to be a valid, lawful reason for a police search."

Aggravated assault charges laid

White River and Wawa are about 90 kilometres apart in northwestern Ontario. (CBC)Provincial police responded Sunday around 4:15 p.m. to a call made near the town of White River reporting that a passenger had been stabbed in the chest by a fellow traveller.

The victim suffered non-life-threatening injuries and was taken to a hospital in Wawa, before he was transferred to a hospital in Sault Ste. Marie, police said.

Police arrested a suspect near White River, a town about 300 kilometres north of Sault Ste. Marie, shortly after he left the bus.

"The suspect in this matter went to the front of the bus and asked to be let off. The bus driver opened the door … and within a very short time thereafter, we were able to arrest the gentleman on the side of Highway 17," said Ontario Provincial Police Const. James Searle in Wawa.

Greyhound 'co-operating fully'

Greyhound spokesperson Abby Wambaugh, speaking from Dallas, Texas, said the company is "co-operating fully" with police in the incident that occurred about 15 kilometres east of White River.

Another bus was provided for the other 13 passengers to continue on their trip.

They continued to their next stop, Thunder Bay, after staying in Wawa until 2 a.m. while police finished their interviews, Searle said.

Passengers shouted warnings

Passenger Anita Daher said she heard a shout that someone was having problems breathing, and something about a knife. She dialled 911, then handed the phone to the bus driver.

Another passenger, Floyd Sabourin of Mobert, Ont., said he was asleep when he woke to a commotion and others shouting that a man was carrying a weapon.

"Everyone was saying, 'He's got a knife,' and that's all I heard. The next stop, he got out and we left him there," he said.

Sabourin said it appeared to him that the man with the knife was bleeding as he left the bus.

Greyhound passengers arriving in Winnipeg on Monday said they were shocked to hear of another bus stabbing, but at least one of them said it won't change the way she travels.

Diane Brewster, who arrived in Winnipeg from Flin Flon, Man., said she's not sure how much more secure one could make bus travel, unless everyone is made to go through metal detectors.

"I would beep every time," she joked, referring to her hip replacement.

Bus attack follows another one in Manitoba

The attack comes less than two months after a Greyhound passenger was arrested following the beheading of Tim McLean, a 22-year-old man from Winnipeg, sparking questions about security on buses.

Vince Weiguang Li, 40, is charged with second-degree murder and undergoing a psychiatric evaluation to see whether he is fit to stand trial. He's scheduled to appear in court Oct. 6.

McLean's family is suing Greyhound and the federal government. The family's lawyer Jay Prober said he's disappointed and astounded that Greyhound has done little to improve bus safety.

"What are they waiting for? Are they waiting for another death? They should get off their butts and make sure passengers are safe," he said.

A Greyhound spokeswoman said the company was expecting to meet this week with Transport Canada to talk about ways to improve bus safety, but later said she was misinformed and there was no meeting set for this week.

A Transport Canada spokeswoman, Maryse Durette, later told CBC News that no meetings had yet been scheduled with Greyhound. She said Transport Canada is waiting for Greyhound to bring forward its risk assessment and security plan. The company received $285,000 to develop the plan under the Transport Canada's Transit-Secure program in April 2007, Durette said.