"We will be defending the case vigorously," Thomas Dungey said Thursday, after Smich appeared in a Hamilton court to face the murder charge.
Smich's arrest came several days after Dellen Millard of Toronto was also charged with first-degree murder.
CBC's Adam Carter, who was in the courtroom Thursday morning, reported that Smich appeared to be nervous and said little during his appearance. He was wearing baggy pants with a baggy T-shirt and white sneakers, and had a shaved head.
Smich had a small cut on his left cheek and some bruising under his eye. He did not appear to have any supporters in the room.
Smich, 25, was arrested in Oakville on Wednesday morning, about an hour before the start of a memorial service for Bosma in Hamilton.
Bosma went missing while on the test drive with the two men, who had answered an online ad. His remains were found earlier this month, burned beyond recognition, at a farm belonging to Millard, of Toronto.
Both Smich and Millard are next expected to appear in court on June 13.
Police still don't have a motive for the killing.
Millard, 27, also faces charges of forcible confinement and theft of a vehicle. His lawyer has said his client will plead not guilty.
Police allege the suspects are the two men who Bosma took for the test drive. The search continues for at least one other suspect.
News of a second arrest, of Smich, came just minutes after the public memorial service for Bosma ended Wednesday.
Smich was arrested while walking near Dorval Drive and Wyecroft Road in Oakville, less than one kilometre from his home.
Court records show Smich has several criminal convictions, including possession for the purpose of trafficking in 2006 and impaired driving in 2010. He is also scheduled to appear in court on a charge of mischief next month.
Suspect's neighbour calls arrest work 'really scary'
Shortly after Smich's 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.”
Capelo, 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.
Andrew 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."