Months after Balin Stewart died, a friend wanted answers about the 16-year-old's fatal stabbing, a jury has heard.
So the teenage girl confronted the boy accused of Balin's murder at his own home.
"I asked why he did it and if he regretted it," the girl told Brisbane Supreme Court on Thursday.
"He said to the first question that he was just so angry, overcome with jealousy and everything, and it was just impulse to grab the knife.
"To the second question he said 'yes, I regret it'."
The boy - who was 17 at the time of the alleged stabbing - has pleaded not guilty to murder after Balin died just metres from his family home on Queensland's Sunshine Coast in January last year.
The boy believed his ex-girlfriend was spending time with Balin and attacked the 16-year-old at Buddina out of jealousy, crown prosecutor Rebecca Marks had earlier told the jury.
Balin died from a stab wound to the heart by a steak knife with a 12-centimetre blade.
Months later, the teenage girl had gathered with friends at a birthday party when the conversation turned to Balin.
The girl then decided to confront the boy accused of murder.
"We were all out the back (at the party) talking about Balin and everything, and how none of us had closure," the girl said.
"I wanted to ask the questions that hadn't been answered."
She walked to the boy's house which was a street away from the party and knocked on the front door.
The boy answered and agreed to answer the girl's questions, she said.
She asked why he did it, if he regretted it and "why bring a knife", the girl told the jury.
Asked if it was a friendly interaction, the girl answered: "I made sure I was nice".
She also asked if he "thinks about what happened" before leaving after small talk, the girl said.
The girl was best friends with the boy's ex-girlfriend, she said.
She said when the boy and ex-girlfriend were together their relationship was "toxic".
"(The boy) was pretty controlling," she said.
The girl said the boy "hated" Balin.
However, she agreed under cross-examination that it would be fair to say Balin did not like the boy.
The girl also agreed that Balin and the boy had each told her separately that they wanted to fight one another.
Earlier, confronting pictures of Balin taken at the morgue were shown in front of his distressed family, prompting a word to the jury from Justice Elizabeth Wilson.
"I probably should say something about those photographs that you just saw," she said.
"They were graphic and confronting though they were attempting to show where the injuries were.
"I direct you that any emotion that you may have felt when seeing these photographs can't have a part to play in your decision."
