Why Diddy's alleged 'drug mule' was granted immunity as he's set to take the stand today

Prosecutors are set to call their final witnesses to the stand during the trial of Sean 'Diddy' Combs today (20 June) before resting their case.

Arguably the most anticipated testimony will be heard during these proceedings, and will come from the rapper's alleged 'drug mule', former Syracuse basketball player Brendan Paul.

He is among several other witnesses who have been granted immunity in exchange for sharing their story of what being a part of Combs' world entailed.

The Bad Boy Records founder, 55, is currently standing trial in New York and is facing charges of racketeering, sex trafficking and transportation to engage in prostitution - all of which he denies.

The court has heard how Combs would enlist his employees and those in his inner circle to procure substances for him ahead of the marathon sex sessions he dubbed 'freak offs'.

Brendan Paul, 25, is set to testify today about his involvement with Diddy (John Lamparski/Getty Images)

According to prosecutors, Brendan Paul is one of the main people who often obtained supplies for these drug-fuelled encounters.

The 25-year-old was arrested at Miami's Opa Locka Airport on 25 March - the same day that federal agents raided Combs mansions - and was found to be in possession of cocaine.

He was initially charged with a felony given the illegal contents of his travel bags, but this was later dropped.

Paul was also named in a lawsuit filed by music producer Rodney Jones, which alleged that the former sportsman acted as Combs 'mule' who procured and distributed 'drugs and guns' for him.

The legal claim also alleged that Jones had 'personally witnessed' Paul either transport, or try to transport, illegal drugs on three occasions.

This is said to have taken place while taking flights between LA, Miami, Virginia, the Caribbean and London, according to the lawsuit.

Discussing why Paul's testimony could prove pivotal for the prosecution, US lawyer Nicole Blank Becker told Fox News: "In this particular case, why [Paul] may be important is because he is allegedly one of the individuals who supplied the drugs. The distribution of drugs, giving other people drugs to make them intoxicated and possibly do more than they would do had they not been intoxicated - that's a predicate felony.

A number of witnesses have been granted immunity in exchange for their testimony (Prince Williams/Wireimage)

"In other words, in order to prove this particular charge of racketeering, there's got to be a number of other felonies that the [prosecution] can connect.

"Another way to prove a predicate felony is bring in the guy who supposedly is the one who was supplying P. Diddy and or his people with what [the government is] gonna say, the drugs that he used [on others.]"

Becker - who represents disgraced rapper R Kelly - went on to explain why Paul has been granted immunity despite the severity of his alleged crimes.

"It is very common, especially in federal cases, that immunity is given to witnesses if they have the information or the insight that they need for their case," Becker said.

"Oftentimes, those individuals who are given immunity, although they may have crimes that they are either facing or faced, they're usually a lot less in the hierarchy of crimes.

"They're usually lower crimes in which the government says, 'You know what, this information that this particular person has is so important that we are willing to forego whatever you've got going on in the criminal section or division now here so that we can have you testify in this bigger case.'

Diddy's former partner Cassie Ventura has also been central to the trial (Jeff Kravitz/FilmMagic)

"The government's goal to get in as much possible information from anybody who knows anything."

Without immunity, Paul may have invoked his Fifth Amendment right to avoid incriminating himself on the stand - whereas without the fear of legal comeback from his testimony, he can speak freely.

According to Becker, the majority of witnesses who have been called to the stand have each had 'a role' in what prosecutors believe was Combs' illegal enterprise.

"Those individual witnesses have their own story, together they form what they are trying to form, which is this step beneath P. Diddy, who's up here," she added.

The trial continues.