Tonight, late-breaking news after a dramatic day in court featuring a young lover's triangle turn ed fatal. One man's girlfriend broke his heart and began dating his best friend. What really happened?... See More
Tonight, late-breaking news after a dramatic day in court featuring a young lover's triangle turn ed fatal. One man's girlfriend broke his heart and began dating his best friend. What really happened? Now, with his fate in the balance, the verdict is in. Here's ABC's Matt Gutman for our series, "Crime and punishment." Did you have any malicious intent to kill Christian Aguilar? No. It was spur of the moment. Reporter: Pedro bravo, on the stand yesterday, trying to convince jurors he's an innocent man, pleading not guilty in the murder of his friend, 18-year-old Christian Aguilar. He's a very good friend of mine. He was something I could open up to. Reporter: What came between the two former best friends, was this woman, who found yourself right in the middle of this lover's triangle. She had broken up with bravo after he graduated high school. But she says he didn't take the news all that well. But Erica wanted to tell Pedro the truth, that she had feelings for his close friend. I liked him because he was a very sensitive point in his life, I suppose. Reporter: But when Pedro found out, prosecutors say, he hatched a plan. The trail of evidence started on the internet with searches, said miss, of alibis. Murder statistics. And fatal doses of sleeping pills. And the prosecution says bravo came out of this Lowe's with what they say is a starter kit for murder. A shovel, to dig a grey. Duct tape to bind him. Gatorade to mix with sleeping kills. He called Christian, saying he was suicide and needed help. And in court, the love-struck bravo, telling the jury, the only person he intended to kill that night was himself. About when did she's suicidal I'duations come into your mind? I was too nervous to do anything with knives. I don't like pain. And I couldn't bring myself to hang myself or anything like that. Reporter: Police and prosecutors never bought that story. And say this feels like it was all about revenge. The case they laid out to the jury begins with two friends meeting for lunch. Then, at 3:00 P.M., they head to this Best Buy. Christian Aguilar buying a Kanye west cd with cash. At 4:11, they pulled into this lot across from the Walmart. And it's at this point, say police, that bravo made his move. For the next three hours, Walmart cameras captured bravo's car sitting here in the parking lot. It's during this time that prosecutors believe, bravo drugged Aguilar. Police say he bound Aguilar using duct tape. And then, he strangled him with his belt. Bravo texted Aguilar's mom, pretending to be Christian. Then, put his phone on airplane mode. But his phone helped police put the pieces together. 48 minutes, he uses his flashlight app that day. What did he turn out in the woods of a private hunt club? His headlights. Reporter: Bravo admitting he his phone was on airplane mode. What was he doing? Why that use of the flashlight? He was burying Aguilar's body. That's where the story ends. The remote forest, Christian's father searched this swamp area and turned up empty. I'm going to do the unthinkable to recover my son. Reporter: But in court, bravo says he never intended to kill him. You intend for him to go on the ground, right? I intended for him to lose his balance. Right. You intend for him to lose his balance. You intend for him to be on the ground. Right? Yes. Your story today is that, during this process, when you've done these two intentional acts to him, his head hits the ground, really hard. I never said that. Reporter: His alibi was that the whole time he did not intend to kill Aguilar but himself. Even writing this suicide note that night. Police say it was after the murder. In court, his demeanor, conversational and combative. Dancing around every word. You didn't find Erica lied to you until Chris admitted he was dating her. He said he was going out with Erica. Oh. There's a difference? I interpreted he was going as a friend. In the car, he told you they were having sex, right? No. That's what you knew when you were in the car with him, right? Pedro bravo on the stand, he was defensive, swirly. Had a nervous laugh. An uncomfortable laugh. These are the kind of things, to me, make a jury doubt his credibility. The kind of things juries can say, I don't believe his story. Reporter: Cagey in court, but in lockup, not so cagey. Allegedly spilling the beans to his cell mate, named michelangelo. I think he said he was going to poison him with a mixture of sleeping pills and pesticide. And mixed with soda or something. I guess soda. His backup plan was to have a knife, you know, to cut his throat. There's a mountain of evidence against Pedro bravo. But michelangelo's testimony is key to this case. Reporter: Telling Angelo, who received in exchange for a reduced sentence, where he hid the shovel he youed to dig aguil Aguilar's grave. They found him, bones and all. And the only cause of death was strangulation. Reporter: A new courtroom twist, saying his cell mate strong armed him and dictated every word. You wrote that. I think I said I wrote this letter, dictated by Michael Angelo. I don't know why you're repeating the question. Reporter: The jury believed none of it. Guilty of first-degree murder. Reporter: Four hours after getting the case, it officially closed it. Count three, guilty, as charged in count three of the indictment. Reporter: And on and on it went. Guilty of all seven counts against him. For the aguilars, no jubilation. Only those stoic stares, turning to tears. Justice and sentencing came swiftly. This is your day of reckoning. The day you answer for your choices. Reporter: Life in prison. For Pedro bravo, murder was the easy part. Getting away with it, much more difficult. For "Nightline," I'm Matt Gutman, in Gainesville, Florida.
This transcript has been automatically generated and may not be 100% accurate.