Supreme Court won't hear appeal for new trial in 'Serial' case. What's next for Adnan Syed?

The Supreme Court decided Monday not to hear an appeal for a new trial from the Maryland man convicted of murder and at the center of the first season of the hit podcast "Serial."

Adnan Syed is serving a life sentence after his 2000 conviction in the murder of his ex-girlfriend Hae Min Lee.

Syed and his legal team were appealing a decision from Maryland's highest court, which denied the man a new trial after lower courts had ruled he deserved one.

U.S. Supreme Court justices did not comment on why they left the Maryland Court of Appeals ruling in place.

Syed and his attorneys have argued that his attorney during his initial murder trial did not provide effective legal counsel when she failed to follow up with a possible alibi witness.

Prosecutors say that Syed killed Lee and buried her body in a Baltimore park in 1999 while both were students at Woodlawn High School. Syed has maintained his innocence.

Here's what to know about the case and what's next for Syed:

What did U.S. Supreme Court rule?

Syed's attorneys petitioned the Supreme Court to hear his case after the Maryland Court of Appeals denied him a new trial.

Their argument centered on the way the Maryland court reviewed the evidence of Syed's trial lawyer's actions when not following up with the potential alibi.

The Maryland Court of Appeals said the lawyer's actions were "deficient" but that, essentially, they wouldn't have changed the outcome of the trial.

The U.S. Supreme Court in effect affirmed this ruling by denying Syed's petition for a writ of certiorari.

Why were Syed's trial attorney's actions 'deficient'?

Cristina Gutierrez, who has since died, defended Syed in trial.

Syed's new attorneys said Gutierrez failed to effectively investigate alibi claims from fellow classmate Asia McClain.

McClain said she talked to Syed at a library during the time frame that prosecutors say he killed Lee.

Gutierrez didn't contact McClain nor did she offer to follow up on McClain's offer to identify other witnesses who saw Syed at the library, his attorneys said.

"Instead, Gutierrez argued that because Syed attended track practice on most days after school, he likely did the same on the day that Lee was killed," his attorneys wrote in their petition.

However, prosecutors had a witness, another classmate Jay Wilds, who said Syed showed him Lee's body in his car.

"In a normal case, it would be left to the jury to determine who is credible: Wilds or McClain. In this case, however, the jury never heard McClain’s testimony," Syed's attorneys wrote.

Wilds, however, made conflicting statements and admitted under oath to lying to police, Syed's attorneys said, but ultimately testified that he helped Syed bury Lee's body.

What's next for Syed?

Syed's defense attorney C. Justin Brown told the Associated Press that there were other legal options for his client and that they were "exploring each and every one of them."

"We are deeply disappointed by the Supreme Court but by no means is this the end of Adnan Syed," he told the news agency.

Rabia Chaudry, an attorney and friend of Syed's family who helped bring his case to the creators of the "Serial" podcast, also said the legal team would be looking into other actions.

She told the AP that his defense could file a habeas petition in federal court or go back to the state court.

"We were just waiting. (The Supreme Court's decision) was just a technicality. Now it’s done, so we can move forward,” she said.

Colin Miller, a law professor at the University of South Carolina who works on a separate podcast that investigates wrongful convictions along with Chaudry, explained a number of possible courses of action for Syed in his blog.

One involves further pursuing claims that cell tower evidence that placed Syed in the park at the time that Wilds said they buried Lee's body is unreliable.

Miller said those claims were not considered for procedural reasons when the Maryland Court of Appeals ruled but could be taken back to lower courts and used to discredit the prosecutor's case.

Another option would be filing a federal habeas corpus petition saying the Court of Appeals violated federal law. However, this would require a higher burden of evidence to prove Syed's case given that certain deadlines have passed and also would need to be filed before working through Maryland courts on the cell tower evidence, Miller said.

Making a case on the cell tower evidence has "a good shot," he said, but with the federal habeas corpus petition, "if it's not brought first, it's going to be lost."

"It's sort of a tough decision at this point," Miller said.

Contributing: The Associated Press. Follow USA TODAY's Ryan Miller on Twitter @RyanW_Miller

This article originally appeared on USA TODAY: Serial case: Adnan Syed denied Supreme Court appeal. What's next?