Adnan Syed, the subject of the popular podcast “Serial,” had his day in court — five of them, to be exact. Now, it's up to a judge to determine whether the man convicted in 2000 of killing his ex-girlfriend will get a new trial.

Syed's attorneys said Tuesday in closing arguments of a weeklong post-conviction hearing that a crucial alibi witness and questionable cellphone records were wrongly overlooked by his original trial lawyer.

“At the end of the day, a mistake was made … not to talk to an alibi witness who could've turned this trial around,” C. Justin Brown told retired Judge Martin P. Welch.

The Maryland attorney general's office maintained that Syed was a calculated killer whose conviction was the only possible outcome. Deputy Attorney General Thiru Vignarajah said he knew the state's position was “not popular.”

“What is popular is not always just,” he said.

Syed, 34, is serving a life sentence for strangling Hae Min Lee, his ex-girlfriend and a Woodlawn High School classmate, and burying her body in Baltimore's Leakin Park. His previous appeals were denied.

Welch did not rule Tuesday, and there is no timetable for when he will issue a written ruling.

In 2014, Syed's case became the focus of the “Serial” podcast, which was downloaded millions of times and won a Peabody Award. The series raised questions about the case, helped uncover new leads and led to spinoffs that probed the case further.

After the hearing, Brown said the case may be the “first ever open-source case.” The evidence was widely disseminated on the Internet, “so people were investigating this case all over the country,” he said.

“I had essentially thousands of investigators working for me,” Brown said in his office Tuesday. “That produced information that we otherwise would not have had.”

The courtroom was packed for each day of the hearing, including dozens of Syed supporters and “Serial” listeners. The hearing also prompted Lee's family to speak out for the first time, issuing statements through the attorney general's office that condemned “those who learn about the case on the Internet” and are pushing for Syed's release. The family said it was “more clear than ever” that Syed was guilty.

Vignarajah said the hearing was “an opportunity for the system to restore faith in the system.”

The hearing, usually a routine step in which attorneys rely primarily on transcripts, became a trial in itself, with attorneys entering numerous documents and affidavits, and expert witnesses debating legal strategy and the reliability of phone records.

The central witness was Asia McClain, a former classmate of Syed's who says she saw him in a library when prosecutors say Lee was being killed.

McClain said she had contacted Syed the day after his arrest, but his attorneys never reached out to her. She was tracked down after his conviction by Syed's family friend and attorney Rabia Chaudry, and signed an affidavit attesting to her account.

But she moved to the West Coast and the defense could not locate her for Syed's attempt to get a new trial in 2012.The former prosecutor on the case, Kevin Urick, testified at the 2012 hearing that he had spoken to McClain and she told him she had been pressured to give the affidavit.

McClain testified last week that she was unaware of that hearing, and only came to realize her importance to the case after her account became central to “Serial.” She disputed that she told Urick she was pressured, and said he tried to talk her out of participating.

Before “Serial,” “I didn't think I was very important at all,” McClain testified. “I came to find out ... maybe it is important.”

Vignarajah asked careful questions throughout the hearing, and called only two witnesses. In his closing argument, he pieced together the answers and documents to put forward a theory to support his contention that Syed's attorneys had made strategic decisions rather than fallen short of effective representation.

A key witness in Syed's original case was Jay Wilds, an acquaintance of Syed's, who said he helped him bury Lee's body in Leakin Park. He cooperated with investigators in exchange for avoiding prison time.

According to Vignarajah, Syed and Wilds had carefully crafted an alibi — calling people and making sure to be seen at certain places.

The original defense attorneys' notes show investigators contacting those alibi witnesses after his arrest, Vignarajah said. Syed did not know at that time that Wilds was cooperating with authorities.

McClain said she saw Syed at the library between 2:15 and 2:35 p.m. But two witnesses said that they saw Lee leaving school alone around 3 p.m.

Vignarajah theorized that if Lee left the school and picked up Syed at the library before he killed her, then McClain's account could have hurt Syed, so his original lawyers ended up not pursuing an alibi strategy.

“Asia McClain was not a weapon for the defense, but a potential weakness,” Vignarajah said.

Vignarajah also suggested that a letter written by McClain could have been put together with Syed's input. He said the high school senior cited details from the case that would not be known until weeks later.

Brown called Vignarajah's presentation “the most convoluted conspiracy theory I have heard put forward by a prosecutor.”

Brown also raised questions about the reliability of cellphone evidence used to place Syed's phone near Leakin Park. A fax cover sheet that accompanied the records from AT&T included a warning about the reliability of incoming calls to pinpoint location, and Brown claimed the cover sheet had been either withheld from the original defense or overlooked by Syed's trial attorneys.

Vignarajah said the cover sheet was a “novel” attempt to discredit cell phone records, and called an FBI specialist in cellphone work who testified that the analysis was accurate and would stand today.

But Brown reached out to the cellphone expert who testified at Syed's 2000 trial, who said the fax sheet concerned him and he no longer stood by his account. Other calls in Syed's phone log raised questions — such as two calls made 27 minutes apart in Woodlawn and Washington's Dupont Circle.

“It's a problem that needs to be addressed,” Brown said. “Everyone in this courtroom has a duty to get to the bottom of the truth.”

Overall, Brown's argument focused on ineffective assistance from Syed's original defense attorney, M. Cristina Gutierrez, who was disbarred a year after Syed's conviction and died in 2004. Former colleagues said that she was crumbling physically and mentally in her later years, and not the top lawyer she once was.

Syed issued a statement, which Brown said his client wrote with his hands shackled, as they have been during the duration of the trial. It said the “events of the past 16 months have filled me with a great sense of hope.”

“I intend to keep fighting to prove my innocence,” Syed said.

jfenton@baltsun.com