Adnan Syed, whose murder trial was dissected on the hit podcast “Serial,” was denied a new trial on Friday by Maryland’s highest court, which reversed a court decision from last year.
Mr. Syed has been serving a life sentence since 2000, when he was convicted of killing Hae Min Lee, 17, a high school classmate whom he had dated. He has maintained his innocence, and the podcast drew widespread attention to his case.
A decision by the Maryland Court of Special Appeals last year found that Mr. Syed had received ineffective legal counsel at his trial and that his murder conviction should be vacated.
But on Friday, Maryland’s highest court, the Court of Appeals, ruled in a 4-to-3 decision that while Mr. Syed’s defense lawyer had been “deficient” in not calling a potential alibi witness to testify during the trial 19 years ago, ultimately Mr. Syed was not “prejudiced” by that deficiency.
Mr. Syed’s lawyer, C. Justin Brown, said in a statement on Friday that he would review other avenues of relief, including federal courts.
Brian E. Frosh, Maryland’s attorney general, said in a statement, “Justice was done for Hae Min Lee and her family.”
[Mr. Syed’s conviction was reinstated two days before the premiere of an HBO series revisiting the case. Here’s what to know before watching.]
In 1999, Ms. Lee’s body was found in a shallow grave in Leakin Park, at Baltimore’s western edge. Mr. Syed was arrested, and in 2000, he was convicted of first-degree murder, robbery, kidnapping and false imprisonment in the death of Ms. Lee.
During the trial, a friend of Mr. Syed said that he had heard him confess to the murder and accompanied him to the park to bury Ms. Lee’s body. But another student, who said she saw Mr. Syed in the library on the afternoon of Ms. Lee’s disappearance, was not called to the stand.
“Serial” debuted in 2014, featuring as its host Sarah Koenig, a former producer with the weekly public radio program “This American Life.” Its first season focused on whether Mr. Syed had received a fair trial. It was downloaded more than 100 million times and won a Peabody Award, turning the case into a topic of national conversation.
In February 2016, lawyers for Mr. Syed argued in postconviction hearings that his original defense lawyer, Maria Cristina Gutierrez, who died in 2004, had been grossly negligent. They also presented new evidence, including testimony from the alibi witness.
But things took a turn on Friday. The appeals court agreed that Ms. Gutierrez erred in failing to investigate the potential alibi witness but disagreed that this additional evidence would have changed the outcome of the case.
Mr. Syed had also tried to claim that his defense lawyer had failed to challenge cellphone location data that had been used by prosecutors in 2000. But the appeals court also rejected this on Friday, essentially because those claims were raised too late in the process.
Mr. Syed’s lawyer, Mr. Brown, said that “we are devastated” by the decision but vowed not to give up.
“The obstacles to getting a new trial are simply too great,” he said. “There was a credible alibi witness who was with Adnan at the precise time of the murder and now the Court of Appeals has said that witness would not have affected the outcome of the proceeding. We think just the opposite is true.”