A 29-year-old man charged with three counts of second-degree murder in connection with the deaths of a mother and two of her children in Ajax, Ont., made a brief appearance in an Oshawa courtroom on Thursday.

Cory Fenn, who appeared to have a black eye and blood on his face, didn't have a lawyer with him. His next court appearance was set for the morning of March 29.

On Thursday morning, Durham police identified the victims as:

Krassimira Pejcinovski, 39.

Roy Pejcinovski, 15.

Venallia Pejcinovski, 13.

Fenn was initially charged with two counts of second-degree murder after the mother and her son were found dead in a home late Wednesday morning, and also one count of attempted murder in connection with her daughter's critical injuries.

The daughter died Wednesday evening in hospital, and the charges were updated Thursday morning, according to Durham Regional Police Const. George Tudos.

Tudos said Thursday the accused had a relationship with the mother, but is not the father of the children.

A courtroom sketch of Fenn, who arrived in court with blood on his face and a black eye. (Pam Davies)

Police had initially said that Fenn did not live at the family's home, but later clarified that he had.

A third sibling, a girl who was not at home at the time of the incident, was found safe, Tudos said.

CBC News has also confirmed that in 2011, Fenn was found guilty of mischief under $5,000, and in 2009 he was found guilty of assaulting a police officer. In both cases, he was sentenced to 12 months' probation.

His Facebook page says he is employed by the Toronto District School Board. The board told CBC News it cannot confirm whether that's true.

Roy Pejcinovski, 15, in an image from his Instagram account, played in goal for the Don Mills Flyers. The president of the club said he was 'an elite athlete' and 'great kid.' (Instagram)

Police called to home

Police were called to the home on Hilling Drive, near Lake Driveway West and Westney Road South, at 11 a.m. ET Wednesday.

A friend of the mother had checked on her and was met at the door by a man, now identified as Fenn, who refused to let her in. Fenn left in a vehicle.

Krassimira Pejcinovski with Cory Fenn in the background. Fenn was charged in his ex-girlfriend's shooting death last week in Ajax. (Facebook)

Durham police's tactical support unit arrested Fenn at an Oshawa home after a search. Officers also located an unoccupied vehicle in the area of Brock Road and Highway 401 that Fenn is believed to have been driving.

During a news conference Thursday morning, Tudos said the victims were all suffering from "obvious signs of trauma," but would not speak on the cause of their deaths. Post-mortems are scheduled for all three, he said.

Neighbours mourn

Neighbour Pat Jordan, a family friend, said he pulled onto Hilling Drive praying that "it was the wrong house."

Jordan, whose daughter was close friends with Venallia, was initially frantic because he thought his daughter might be at the Pejcinovski house.

"I almost got arrested yesterday because I crossed the yellow line," he said, learning later that his daughter had changed her mind and gone to a different friend's house.

Venallia Pejcinovski, seen in a picture posted to Twitter in 2015. (Twitter)

He described Venallia as "a heartfelt soul. She was happy, she was active, interactive with everybody."

Her mother, he said, was a "great parent" who once looked after his daughters when he and his wife went on a weekend getaway.

"She was so good-hearted, so good-hearted. That whole family was amazing," said Jordan.

'I'm in shock'

Peter MacInnis, president of the Don Mills Flyers, told CBC Toronto on Wednesday night that Roy Pejcinovski played for the hockey club, and was "an elite athlete, [a] great kid" who played goalie the past five years.

A forensic investigative services truck sits parked outside an Ajax, Ont., home on Wednesday afternoon. (Chris Glover/CBC)

Roy would have been eligible and a high pick for the OHL draft next year, according to MacInnis.

"I'm in shock. I can't believe it, quite frankly," MacInnis said.

"I've been watching the kid play in our rinks since he's nine years old, and then all of a sudden he's not there. It's tough."

The Don Mills Flyers are deeply saddened by the tragic loss of Bantam goaltender Roy Pejcinovski. Roy was an outstanding goalie, teammate, and above all person. Our thoughts and prayers are with the Pejcinovski family at this time. An official release will be posted tomorrow. <a href="https://t.co/1jKzE3Nl3T">pic.twitter.com/1jKzE3Nl3T</a> —@DMFlyersAAA

Boy, father were close, coach says

MacInnis said the boy was close to his father, who used to stand with MacInnis and the general manager to watch games.

"They're huge supporters of each other," MacInnis said. "They adore each other."

He said the boy's parents were no longer together, which was difficult on the boy.

"But he and his dad are really tight, and I'm sure the dad right now is absolutely destroyed."