09/17/2017 11:41 EDT | Updated 09/17/2017 15:21 EDT

Father of boy who was the subject of an Amber Alert taken to hospital

MONTREAL — A man who was arrested after police found his six-year-old son, who had been the subject of an Amber Alert, remains in an Ontario hospital.

The boy vanished from St-Eustache, Que., on Thursday and his father was apprehended in Ontario nearly 24 hours later. By then, the body of the boy's mother had also been discovered in the family home.

Ontario Provincial Police say the man suffered injuries that required medical assessment and he was sent to hospital Saturday.

The man appeared by videolink earlier in the day from a police station in Renfrew, Ont., where he had been held since his arrest on Friday night.

Quebec provincial police have not responded to requests for comment about what charges the man might face when he returns to his home province.

As of Sunday afternoon, it was not yet clear when the man would be transferred to Quebec police.

"This man will be back in Quebec when his health conditions are better," spokesman Claude Denis said.

Meanwhile, volunteers and police officers continued their search Sunday for a 71-year-old man who has been missing from Lachute, Que., west of Montreal, since Friday.

Yvon Lacasse previously used the car in which the six-year-old boy was found safe.

Denis says investigators now want to speak to a motorcyclist who could be a useful witness and are asking for help from the public.

Police have images from a surveillance camera that show a motorcyclist in Lachute who may have seen Lacasse's car Thursday at about 6 p.m. — the time police say the car was stolen.

"In the pictures we can see the motorcyclist and we can also see the car of Mr. Lacasse," Denis said Sunday.

Denis is also asking motorists, campers and others living in the area between Lachute and Rouyn-Noranda, Que., to check ditches, cabins and backyards as the search for missing man continues.

Lacasse is bald with brown eyes, 5 feet 5 inches tall, and weighs just under 100 pounds.

Police are asking anyone who thinks they may have seen him to call 911.