An alibi witness who was never called, cell phone data that was misrepresented and other legal failures justify a new trial for Adnan Syed, his defense lawyer argued Tuesday, closing an unusual hearing prompted by a popular podcast that turned millions of listeners into armchair detectives.

Deputy Attorney General Thiru Vignarajah countered that the evidence is "overwhelming" that Syed was properly convicted and sentenced to life in prison for the 1999 strangling death of his high school girlfriend Hae Min Lee.

"This is not a popular position, but the state's role is to do justice," the prosecutor said, acknowledging the popularity of "Serial," a public radio podcast that extensively re-examined the long-closed case.

Earlier Tuesday, defense attorney Justin Brown urged Judge Martin Welch to grant Syed a new trial.

"We proved our case. We did exactly what we said we would. I believe we met our burden and that Mr. Syed deserves a new trial," Brown argued.

He said cell tower data linking Syed to Lee's burial site was misleading because prosecutors presented it to jurors without a cover sheet warning that information about incoming calls was unreliable, and also withheld that information from Syed's trial attorneys.

Moreover, Brown said Syed's trial lawyer was ineffective because she didn't contact Asia McClain, now Asia Chapman, an alibi witness who said she was with Syed at a public library during the time Lee was killed.

"A mistake was made not to talk to an alibi witness who could have turned this trial around," Brown said, calling Chapman "earnest," ''compelling" and "extremely credible."

Brown said, "If Mr. Syed was with Ms. McClain at the library on Jan. 12, 1999, he didn't kill Hae Min Lee. He couldn't have."

Prosecutors dismissed the defense arguments, arguing that Syed wasn't convicted because of ineffective counsel or faulty evidence, but because "the evidence was overwhelming, and because he did it."

Vignarajah said Syed's trial attorney, Cristina Gutierrez, put on a "passionate, vigorous defense," and "poured every ounce of her great talents into Mr. Syed." Syed himself said so, the prosecutor said, writing in a letter to the trial judge during his original proceedings that Gutierrez's "hard work, determination and belief in my innocence assures me I'm in the best hands."

Vignarajah was to continue his arguments after a brief lunch break.