A Broward jury on Tuesday convicted a Pembroke Pines man of the murder of his adoptive mother, rejecting a defense claim that he had consensual sex with the victim and then passed out while someone else killed her.

Gerard Lopes Belmonte, 23, was found guilty of second-degree murder after jurors deliberated for five hours Tuesday. He faces a maximum of life in prison when he's sentenced Oct. 10.

The verdict ended a one-week trial that devastated the victim's family. Lopes was Natalie Belmonte's first cousin, and she adopted him in 2000 after his father, her uncle, died in their native Guyana. A real estate agent in Weston, Belmonte, 43, had two biological children, a daughter and son who looked at Lopes as a big brother.

Witnesses testified that Belmonte treated Lopes no differently than she treated her other children, and prosecutors introduced as evidence birthday cards the two exchanged in the months leading up to Belmonte's murder.

"You're the best mother a son could have," Lopes wrote to Belmonte on her birthday.

"I am very proud of the man you are becoming," Belmonte wrote on his 21st birthday. "I love you. Mom."

The exchange stood in sharp contrast to the charges made by prosecutors and the explanations proposed by the defense. Prosecutors presented evidence that Lopes and Belmonte attended a graduation party for a mutual friend on July 16, 2011. They arrived home at 2:49 the next morning.

At some point after they got home, Lopes attacked Belmonte, according to prosecutors. His semen was later found in her body, and the victim's sister testified that the only way it could have gotten there was against Belmonte's will.

Prosecutors said Lopes was the man seen on a neighbor's surveillance video loading Belmonte's body into the trunk of her Lexus and driving off before dawn on July 17, 2011. Belmonte's body was found three days later in a wooded area less than a mile from their home. Lopes was charged the same day.

Family members, including the victim's parents, a biological son and daughter, and the victim's sister, left the courtroom without commenting Tuesday.

Defense lawyer Jose Reyes painted the verdict as a partial victory for his client. Lopes had been charged with first-degree murder, which carries a mandatory life sentence. But the jury found Lopes guilty of second-degree murder, apparently deciding that prosecutors failed to prove the killing of Belmonte was premeditated.

Under Florida law, a murder can be considered first-degree if it is committed while the defendant is in the process of committing another felony, and prosecutors had hoped the jury would connect the murder of Belmonte with her alleged rape. But Broward Circuit Judge Matthew Destry did not allow jurors to hear a standard instruction that would have made that connection clear.

Reyes said he intends to appeal the verdict.

"We feel there's plenty of error in the case," said Reyes. He said the judge should not have removed Reyes' original co-counsel, Samantha Epstein, on the day of opening statements, and should not have allowed the victim's sister, Michaela Teixeira, to testify about her opinion as to whether Belmonte would have consensual sex with Lopes.

"They allowed opinion testimony on the sexual battery issue," Reyes said. "That's normally not done."

Witnesses are typically not allowed to express their opinions unless they are experts in a recognized field of study. Reyes said Teixeira was not an expert witness and should not have been allowed to present her opinion to the jury.

"The appeal will start immediately after the day of the sentence," Reyes said.

If Lopes succeeds in his appeal, he cannot be tried for first-degree murder again.

raolmeda@tribune.com, 954-356-4457 or Twitter @SSCourts