Adnan Syed, who spent more than two decades in prison while fighting charges that he had killed his former high school girlfriend, will remain free after a judge in Baltimore on Thursday reduced his sentence to time served.

The ruling effectively brought an end to a sensational case that received widespread attention starting in 2014, when the first season of the hit podcast “Serial” raised questions about Mr. Syed’s conviction in the 1999 killing of Hae Min Lee, 18. The podcast was downloaded more than 100 million times in its first year and jump-started Mr. Syed’s fight for his freedom, which ping-ponged through the court system for more than a decade.

Judge Jennifer Schiffer of Baltimore City Circuit Court issued the ruling after prosecutors in Baltimore withdrew a motion last week to vacate his murder conviction. Mr. Syed was released from prison in 2022 after a different judge vacated the conviction, and the charges against him were dropped later that year. But his conviction was later reinstated, and last year Maryland’s highest court ordered a redoing of the hearing that initially freed him.

Judge Schiffer, who presided over that hearing on Feb. 26, said in her decision on Thursday that Mr. Syed, 43, “is not a danger to the public” and that “the interests of justice will be better served by a reduced sentence” of time served. Mr. Syed will enter a period of five years of “supervised probation,” according to her ruling.

Ms. Lee’s brother and mother had urged the court to uphold Mr. Syed’s life sentence. David Sanford, a lawyer for the family, criticized the ruling on Thursday.

“Absolutely nothing changes the fact that Mr. Syed remains convicted of first-degree premeditated murder due to overwhelming direct and circumstantial evidence,” he said in a statement. “We hope that one day Mr. Syed can summon the courage to take responsibility for his crime and express sincere remorse.”

Erica J. Suter, Mr. Syed’s lawyer, responded to the decision with “joy and relief.”

“He was a model candidate for a sentence reduction,” she said in a statement. “Adnan is committed to continuing to be a productive member of his community and living a life centered around his family.”

The ruling came after Mr. Syed and relatives of Ms. Lee testified at an emotional hearing last week.

“Your honor, I humbly ask that you continue to allow me to be with my family and friends as I have been the past two and a half years,” Mr. Syed said. “I humbly request to remain free so I can continue to contribute to society and build a meaningful life outside of incarceration.”

Ms. Suter argued that Mr. Syed did not pose a danger to the public. He took advantage of education programs in prison, has been married for five years and had earned a promotion in his job, she said. She also asked the judge to consider Mr. Syed’s age — 17 — at the time of the crime and a statement from the judge who first sentenced him calling for his punishment to be reduced.

“He is a walking demonstration of someone who is rehabilitated,” Ms. Suter said. “He hasn’t gotten so much as a parking ticket in three years. I wish I could say the same.”

Mr. Sanford, the lawyer for Ms. Lee’s family, argued that Mr. Syed’s sentence should not be reduced, in part because he was found guilty in 2000 and because the “momentum” to release him was generated by media coverage.

In 2014, “Serial” cast doubts on parts of the case, including the credibility of cellphone tower records used in the investigation. It also raised questions about the existence of an alibi witness who had not been asked to testify.

The podcast generated global interest in the case and won a Peabody award. (In 2020, The New York Times Company bought Serial Productions, the company behind the podcast.)

An appeals court vacated Mr. Syed’s conviction in 2018 and said he should be granted a new trial, but he remained incarcerated and the decision was reversed in 2019.

Young Lee, Ms. Lee’s brother, said at the hearing on Feb. 26 that, because of the media interest in the case decades after her murder, he felt as if he were “living it over and over again.”

Mr. Syed was emotional as he acknowledged the pain Ms. Lee’s family had suffered.

“When I came home, there was a huge media spotlight,” he said, referring to his release from prison in 2022. “I remember Young saying — when they released me — how painful that was. I said to myself, ‘I’m going to keep my head down and focus on my job.’ I never did any interview in large part because it caused them pain.”

Before the hearing on Feb. 26, the office of Ivan J. Bates, the Baltimore City state’s attorney, said it would abandon the effort to cancel Mr. Syed’s conviction. The motion to vacate the conviction, which was filed by Mr. Bates’s predecessor, Marilyn Mosby, contained “falsehoods and misleading statements,” he said.

It was a surprising move because Mr. Bates, who was sworn in as state’s attorney in January 2023, had promised during an unsuccessful campaign for the office in 2018 to drop the prosecution of Mr. Syed.

Even so, Mr. Bates said at the hearing on Feb. 26 that Mr. Syed should not return to prison.

“While I cannot ethically put forth the motion to vacate, I can stand and say I support Mr. Syed receiving a modification in his sentence to time served,” he said.

In a statement on Thursday, Mr. Bates said the ruling to reduce Mr. Syed’s sentence was a “just outcome.”

“I hope the Lee family can find peace and healing in the aftermath of this challenging experience,” he said.

Michael Levenson contributed reporting.