The Maryland Court of Special Appeals voted 2-1 to find that Syed's "Sixth Amendment right to effective assistance of counsel was violated by trial counsel's failure to investigate McClain as a potential alibi witness".
Chinese nationals living in the United States have also begun to disappear under suspicious circumstances, although unlike previous targets, "they were not high-profile folks", said one former US intelligence official.
In 2016, Retired Baltimore Circuit Judge Martin Welch also ruled that because Syed's lawyer didn't challenge the very testimony in the case that became the focal point of "Serial", he deserved a new shot at freedom, the Associated Press reported. However, prosecutors appealed that decision to the appellate court.
That potential alibi witness, Asia McClain, claimed to see Syed in their high school library during the time prosecutors said Lee was murdered.
The first season of Serial premiered in 2014, and called into question a number of facts surrounding Syed's case.
Trump administration to add citizenship question to 2020 census
A group of 19 Democratic attorneys-general told Mr Ross this month that including the question would be unconstitutional. Census data is used to decide things like allocation of federal funds and apportionment of congressional seats.
The show attracted millions of listeners and shattered records for the number of times a podcast has been streamed or downloaded. If it's appealed, it would be many months before Syed would learn whether his conviction stands and whether he would be granted a new trial, according to the Baltimore Sun.
The massive popularity of Serial drew attention to Syed's case - and supporters for Syed, who has continually maintained his innocence.
Maryland Attorney General Brian Frosh said in a statement his office is "currently reviewing today's decision to determine next steps".
Brown said he is pleased by the ruling and said he hopes the state won't appeal it.
A new trial is not yet written in stone.
Brown said if the case were to go to trial, "we like our chances - we like them a lot".