Promininent law professor Daniel Markel, 41, was found shot dead in his driveway two years ago in what police believe was a murder for hire plot

A woman who police in Florida believe facilitated the murder-for-hire plot of a prominent Florida State University law professor has been arrested.

Katie Magbanua, 31, was picked up by police in Davie, Florida, on Saturday following a traffic stop outside a busy shopping plaza.

Daniel Markel, 41, a nationally renowned criminal justice scholar, was killed after being shot twice in the head in July 2014 as he sat in his car in his garage.

Detectives say Magbanua is the link between Markel's ex-wife, Wendi Adelson, and the two men accused of killing him.

She had a romantic relationship with the her brother, Chris, and had two children with Sigfredo Garcia, one of the alleged gunmen.

Tallahassee police have long alleged that the motive for the murder was the bitter divorce between Markel and Adelson.

Adelson's family's were desperate to have their daughter and the couple's two children move closer to them in south Florida, but Markel had successfully fought his ex-wife's attempt to relocate with the children.

In May of this year, police arrested Sigfredo Garcia and Luis Rivera, two south Florida men with criminal histories, and charged them in Markel's murder. Both have pleaded not guilty.

Katie Magbanua, 31, was picked up by police in Davie, Florida, on Saturday following a traffic stop outside a busy shopping plaza. She is facing first-degree murder charges

But it is Magbanua, who was arrested on a warrant for first-degree murder, who is is suspected of being the link between the two alleged hit men and Adelson's family.

Police allege that Garcia and Rivera were 'enlisted to commit this egregious act.'

In a police affidavit authorities state they believe Garcia and Rivera traveled from Miami to Tallahassee two days before the murder to shoot Markel in broad daylight.

They then drove back to Miami immediately following the murder.

The first person Garcia called after the murder, police say, was Magbanua.

Here, the relationship becomes complicated. Magbanua is not only the mother of Garcia's two children but she also had a romantic relationship with Adelson's brother, Charlie.

After Wendi Adelson (pictured) divorced Markel, she left for South Florida with the couple's children, but was forced to return after a court ruling which prosecutors say could have motivated the murder

Garcia and Rivera were arrested on charges of murder but there was not enough evidence to proceed against anyone other than the two alleged hit men.

Garcia's attorney, Saam Zangeneh, told ABC News that Magbanua's arrest was not unexpected, but that it strikes him as last-gasp attempt by law enforcement to try to prove their theory of the crime after two years of investigation.

'Desperate times call for desperate measures,' he said. 'The prosecution has made her a focal point of this investigation. I am eager to read the arrest warrant and see why Katie was arrested.'

An affidavit for Magbanua's arrest alleges she had deposited over $50,000 in cash into her bank account in the 16 months after the murder. She also began receiving regular checks from the Adelson family's dental clinic.

Earlier this month, video footage was aired showing an undercover agent who posed as Rivera's brother confronting Markel's former mother-in-law, Donna Adelson as part of a sting operation.

The agent approached Donna on the street and said that his brother was in need of money, and asked her for $5,000 to help out the man.

Prosecutors say Sigfredo Garcia (left) killed Markel on request from his wife's family after the couple divorced. Charles Adelson (right), the wife's brother, knew Garcia and was dating the mother of his children

In May of this year, police arrested Sigfredo Garcia (left) and Luis Rivera (right), two south Florida men with criminal histories, and charged them in Markel's murder. Both have pleaded not guilty

Donna appears shocked and taken aback in video of the interaction which was revealed for the first time ever on 20/20, but not as shocked as police after what happened next.

According to police documents, authorities allege that soon after Donna met the agent claiming to be Rivera's brother, her son Charlie called his then-girlfriend Magbanua and said to her: 'You better kill him, because he’s going to be a big problem... if you can't do it I'll have someone else do it.'

Video of the encounter between Donna and the undercover agent shows the man approaching her on the street and saying: 'I wanted to let you know that my brother… he helped your family with this problem your family had up north. He’s going through some rough times and I want to make sure that you take care of what he’s going through.'

June Umchinda (right), 27, said she doesn't believe that Adelson or other family members paid two career criminals to carry out the 2014 killing of Daniel Markel

A stunned Donna responds to this by saying: 'You’re scaring me. I don’t know what you’re talking about.'

That is when the agent hands over the envelope with his request for money and Donna walks away.

In another phone call made shortly after the sting, police allege that Charlie told his mother she should just pay the money as 'a charity.'

Magbanua also reached out to Garcia after the sting according to police.

In June, June Umchinda, 27, a Thailand-born credit union worker who started dating playboy periodontist Charles Adelson eight months prior, told Daily Mail Online in an exclusive interview she doesn't believe the theory that Adelson or other family members paid the two men to carry out the killing of Markel.

'There's no way Charlie or anyone in the family is involved,' she said while standing outside Adelson's canal house in Fort Lauderdale. 'They're all so nice.

Detectives believe that the close-knit Adelson family plotted to have Markel killed after he dragged Wendi away from where they were living in South Florida

'I mean, he hasn't been saying anything about this. I haven't asked about it. But I know he's been under intense pressure over the last couple weeks and I assumed it was something having to do with work.

'I've gone to family dinners and they never talk about what happened to Wendi's ex-husband. I did ask once and Charlie said he was murdered. That was it.

'But I'm practically living with Charlie and I'm not worried. He's very nice and not violent at all.'

No one in the Adelson family has been charged in connection with Markel's murder, and their attorneys have described allegations by police that the family was involved in the killing as 'fanciful fiction.'

Police say a light-colored Prius was tailing Markel that day, from the time he dropped his children off in daycare then stopped by a gym for his morning workout