Petra was last seen by a relative in Highland Falls, New York on January 7, 2006. She paid her cellular phone bill and went shopping at the mall with a friend that day. Her relative reported her missing in February after not seeing her for several weeks. When questioned, Petra's husband of four years, William Muhammad, said he didn't know her whereabouts. He said he hadn't reported her missing because she had left him for short periods before and he assumed she had done so again. He said she took simply her belongings and moved out.

Petra was a student at the State University of New York (SUNY) Orange in Newburgh, New York at the time of her disappearance, studying for a degree in diagnostic imaging with hopes of becoming an X-ray technician. She also held a part-time cashier's job, and was about to sign a lease for an apartment. It is uncharacteristic of her to leave without warning. Authorities suspected foul play from early on in the investigation. The Muhammads have a young son together and lived in a home in the 30 block of Schneider Avenue in 2006; it is owned by William's parents. Police obtained warrants to search the family's home and camper, car and pickup truck. When they searched the home they found no signs of foul play, but they did find a doll with a noose around its neck.

Petra and William were in the process of a divorce at the time of her disappearance. Divorce court hearings were scheduled for January 11 and January 25, but Petra and William both missed them and the divorce case was dismissed as a result. The couple also missed family court hearings after Petra's disappearance; the family court was investigating allegations that William abused their son. The police were called to the Muhammads' home once in response to a domestic dispute, but no arrests were made. Four months before her disappearance, Petra sought an order of protection from William. She told a judge her husband had pushed and shoved her, hit her in the face, threatened to kill her, locked her and their child out of the house, and disabled the phone to keep her from calling for help. An order was granted, prohibiting William from harassing Petra.

William has been uncooperative in the investigation into Petra's disappearance, and authorities believe he may have valuable information he's not sharing. He has not been identified as a suspect in his wife's case, however.

Petra was raised by various relatives other than her parents in Grenada. She moved to Trinidad at age 14, then moved to the United States at age 24 and married William, whom she'd met two years earlier. His former name is William Jackson; he changed his surname after converting to Islam. Petra's loved ones do not believe she would have willingly abandoned her son; they think she met with foul play and is deceased. Her case remains unsolved.