But there were still no clues, at least publicly, as to the motive behind Friday's attack.
Police said a 49-year-old man was taken into custody Saturday night. He was still being questioned and had not been charged as of late Sunday afternoon.
The arrest came a few hours after an explosive device was found and detonated with a police water cannon at a small business northeast of downtown. No one was injured in that incident, although police said there was extensive damage to the building.
Superintendent Danny Smyth of the Winnipeg Police Service said the incident is connected to a bomb that was sent to the Petersen King law firm south of downtown Friday, which exploded and caused severe injuries to family law practitioner Maria Mitousis.
"I know (investigators) have made a solid link ... but I'm really not prepared to get into that detail right now," Smyth told reporters Sunday.
Mitousis was rushed to hospital in critical condition after the blast with what police called injuries to her upper body. A source in the legal community told The Canadian Press she underwent surgery and had lost one hand.
Colleagues of the 38-year-old set up a fundraising website which had raised almost $15,000 in little over 24 hours. The site said Mitousis faces "a long road to recovery."
Smyth said Mitousis was able to speak to investigators Saturday.
"I think she was able to provide a fair bit of information to our investigators, but I'm certainly not prepared to speak publicly on that right now," he said.
Police continued to stress Sunday that the bombings were targeted and not a general attack on the legal profession or the public at large. They had not yet determined whether Mitousis herself was the target, or if it was some other worker in the boutique law firm where she is an associate.
The explosion Friday caused the Law Society of Manitoba to warn its members to keep an eye out for suspicious packages. Police handled more than a dozen calls about suspicious packages on Friday and the weekend, but virtually all were harmless.
Mitousis was injured days after her boyfriend, Barry Gorlick, was stripped of his licence to practice law. He had worked at another firm and pleaded guilty to misappropriating money from two clients and lying to a third. Police said they were aware of what happened to Gorlick, but gave no indication there was a connection between his disbarrment and the bombing.