Smich, who according to Kinsella is known to police, will be charged with first-degree murder. No further details about him were released by police.
Dellen Millard, 27, is already facing a charge of first-degree murder in Bosma's death. Police said at a news conference this afternoon that a third suspect is still being sought.
News of a second arrest came just minutes after a public memorial service for Bosma ended.
Smich was arrested while walking near Dorval Drive and Wyecroft Road in Oakville this morning. Police were also at a home listed as being owned by the Smich family earlier this morning. The arrest was made less than one kilometre from the home.
Court records show that Smich has several criminal convictions, including possession for the purpose of trafficking in 2006 and impaired driving in 2010. He was also scheduled to appear in court on a charge of mischief next month.
Shortly after the arrest, police moved in on a home in Oakville owned by Maria Smich-Grygorcewicz on Montrose Abbey Drive. Hamilton police confirmed the search at that address was related to the Bosma case.
Neighbours told CBC News in Hamilton that police arrived at the Smich home at about 9 a.m. Officers were still at the house in the afternoon.
Tactical officers and plainclothes police were seen coming and going from the home and gathered around vehicles outside. A neighbour reported seeing officers with guns drawn on the street.
The Hamilton police forensics van was also at the house, along with another van. Neighbours said they had not seen any police activity prior to today. The home is a detached two-door garage home. The current residents bought the home about 10 years ago.
Stefania Capelo, who lives across the street, said she saw police crews investigate the home mid-morning on Wednesday.
“It was a really surreal thing. It happened very quickly and I just kind of watched from my front door. It wasn't a big show, if that's what you're asking.”
Capeloa, 34, said she doesn't know the individuals who live at the house.
“I just thought the house was rented, and I've always seen people come and go from there. I don't know them at all.”
The current tenants, she added, appear to be young men in their 20s.
“They are friends. They kind of hang out on the veranda. Things that young 20-year-olds would do.”
She described her street as quiet, suburban and filled with young families.
"It's really scary that something like this would happen in this neighbourhood."
Smich's father 'shocked'
CBC News reached Andrew Smich, Mark's father, on Wednesday afternoon.
"What can I say? I'm shocked," he said of his son's arrest, his voice trembling.
The elder Smich said he last saw his son on Sunday, as the family gathered for the wedding of his daughter — Mark's sister.
"He was normal," he said of his son's behaviour at the event. "I didn't see any change, any difference."
When asked if he knew whether Mark had associated with Dellen Millard, Smich responded, “Absolutely not.”
“He’s not living with me. He’s living with his mother in Oakville.”
Smich said he wouldn't answer further questions, including ones about whether his son had ever been in trouble with the law.
"I'm not ready to talk."
Suspects accompanied Bosma on test drive, police say
Bosma, 32, disappeared May 6 after he went on a test drive of a pickup truck he had for sale with two men, and police announced on May 14 that they had discovered his remains on the Ayr farm of Millard.
At today's news conference, Kinsella said police believe Millard and Smich were the men who went with Bosma on the test drive. Kinsella also said the second vehicle caught on video camera following the pickup on the test drive had been identified. It was a GMC Yukon owned by Millard. It has been seized by police and is being analyzed for evidence.
After Bosma's remains were found, police said they were "burned beyond recognition."
Police located an incinerator on the farm that they say Millard, the heir to a family aviation dynasty, purchased last July. The machine, known as "The Eliminator," is used to cremate livestock, but police said Millard didn't own any animals.
A small memorial to Bosma is growing near the gated entrance to Millard's farm, with new bouquets of flowers being added.
Bosma was remembered at a public memorial at Carmen's banquet hall on Wednesday morning attended by more than 1,000 people.
"On May 6 our lives changed forever," Bosma's widow, Sharlene, told those in attendance. "What happened to him was not God's doing. I know that if it wasn't Tim it could have been another man and another man's family. What if they didn't have the support that we have. I couldn't be here without all of you. Evil came to pass. We have seen there is far more good on this earth. I believe, especially in this case, good will overcome the evil"
His sister, Michelle DenBak, also had a message for the more than 1,000 people jammed into the hall, where the Bosmas celebrated their wedding three years ago.
"Our family will not be ripped apart. Our family will not lose hope," she said. "I urge you today to get your act together. Spend more time with your family. Spend more time with your kids. Spend more time with your spouse. Don't be too proud to say I'm sorry."