Accused Hitman in FSU Murder Case Now Cooperating With Authorities

— -- In a stunning development, one of the men accused of killing Florida State University law professor Dan Markel has "flipped," pleading guilty to second-degree murder and cooperating with investigators in exchange for a more lenient sentence.

At a hearing today in Tallahassee, Florida, Luis Rivera, 33, changed his original not guilty plea as part of a plea agreement with prosecutors.

Markel was shot and killed in the garage of his Tallahassee home in 2014 in what police have called a murder for hire scheme. Authorities allege that the family of Markel’s ex-wife Wendi Adelson hatched the plot in the wake of the couple’s bitter divorce. Police say that Adelson’s family had a “desperate desire” for Wendi Adelson and her two children to move closer to them in South Florida and that Markel was standing in the way.

Police say they were able to trace a Toyota Prius seen leaving the crime scene to Rivera and his childhood friend Sigfredo Garcia, both of whom lived in the Miami area. Authorities say Rivera was known as a leader in the North Miami chapter of the Latin Kings gang. GPS and cellphone data revealed that Rivera and Garcia had traveled in the Prius to Tallahassee at the time of Markel’s murder, according to police.

This May, Rivera and Garcia were charged in Markel’s killing. Both pleaded not guilty to first-degree murder at the time.

In exchange for his cooperation, Rivera, who originally faced the death penalty for Markel’s murder, was sentenced to 19 years in prison. The sentence will run concurrent with the 12-year federal sentence Rivera is presently serving for a gang-related conviction. At today’s hearing, Chief Assistant State Attorney Georgia Cappleman said Rivera had told investigators where the murder weapon is located, but it has not yet been recovered. Cappleman also named Garcia as the triggerman in Markel’s murder.

In response to Rivera’s plea deal, Garcia’s attorney, Saam Zanganeh, told ABC News that prosecutors gave away too much “for the word of a federally convicted gang member.”

Cappleman said Rivera has already provided some information to authorities, who are hopeful that his cooperation will lead to convictions against others involved in the alleged murder for hire plot.

Cappleman said Rivera’s information led to the arrest of one of those suspects, Katherine Magbanua, who was taken into custody this weekend on a warrant for first-degree murder. According to her arrest affidavit, police believe “the murder was arranged through” Magbanua and that she “has been romantically involved with both Garcia and Charlie Adelson, the victim’s former brother-in-law.”

The affidavit states that Magbanua made cash deposits of more than $56,000 in the 16 months following the murder. After Rivera was incarcerated on the unrelated charge he was ultimately convicted of, police say he told someone in a phone conversation that “Magbanua had all the money and that she needed to be nice to [Rivera] and give him bail money.”

In response to Magbanua’s arrest, her attorney, Tara Kawass, said, "Katherine is a single mom who has no prior convictions. There was no reason to arrest her like this. Our sole priority right now is getting her on bond so she can take care of her two kids."

Arrest affidavits were submitted for Magbanua and Charles Adelson in May but prosecutors declined to file charges at the time, citing a lack of evidence.

In a statement, Charles Adelson's attorney, David Oscar Markus, said of today's deal with Rivera, "The prosecution admittedly didn't have enough evidence so it went out and bought some by giving away the farm to a murderer. This convicted gangster knows the game and would have said anything not to come out of prison in a box. The prosecution literally threatened him with the needle to get this testimony. That's not a search for the truth. That's a deal with the devil."

No member of the Adelson family has been charged in connection with Markel’s murder.

Attorneys for the Adelsons say allegations that the family was involved are nothing more than “fanciful fiction.”