Michael Clarke Duncan's sister has launched an investigation over allegations the actor's former fiancee Omarosa Manigault manipulated The Green Mile star into re-writing his will in the months leading up to his death.

The 54 year old passed away in September (12), following a heart attack, and now his sibling Judy Duncan has hired a lawyer to determine whether the actor was of sound mind when he altered his estate plan in April, 2012 and declared Manigault the main beneficiary.

However, reality Tv star Manigault insists she has had nothing to do with the actor's estate, and has made allegations of her own against Duncan.

She tells Tmz.com, "I don't control the estate or the finances and Judy knows it.

"If you saw all of her emails and texts to me you would see that she is just trying to get money from me, and threatened going to the press if I did not give it to her and that is a crime!"

Manigault is also locked in a dispute with singer Latoya Jackson, who suggested the reality star was been involved in Duncan's death during an exit interview on Tv show Celebrity Apprentice, on which the two women were recent rivals.

Manigault has threatened to sue Jackson if she does not make an official apology for her remarks.