PHOENIX -- Phoenix police have arrested the boyfriend of a pregnant woman who was murdered in a North Phoenix apartment on Wednesday.
The suspect is Dwanddarrius J. Robinson, 21. The victim is Shaniqua Hall, also 21.
Robinson is charged with two counts of premeditated first-degree murder, arson of an occupied structure and kidnapping.
The multiple murder charges are for Hall and her unborn child.
"It appears to be a very brutal homicide scene," said Sgt. Trent Crump with the Phoenix Police Department. "This is a scene in which the victim was duct taped. The victim was bound and it appears the victim is what was set on fire in this particular case."
The victim's family told police that Robinson was the father of the unborn baby and that he and Hall also have a 2-year-old child together. That child, who is now with Hall's family, was in the apartment when Hall was killed, but investigators don't know if he or she witnessed anything.
Police said Robinson is the one who called 911 to report the fire. He was on scene when police arrived and remained there on his own. He was taken into custody at the scene on Wednesday night by homicide detectives.
"Our investigators have learned that he purchased duct tape just a few hours prior to the homicide, along with an accelerant - lighter fluid, at a nearby store."
Robinson was in possession of a handcuff key and the victim in this case was handcuffed, according to police. Police said Robinson explained the key, telling them he is a security guard. Police have not yet verified that.
According to police, Hall was bound and set on fire, although investigators are not sure if she was dead before the fire or if the fire is what killed her.
"We don't know the particular order in which everything happened and we will wait for an autopsy to tell us. We don't have any information at least at this point...that it is anything other than her body set on fire that may be what killed her."
The exact cause of death will be determined by the medical examiner.
Phoenix Fire Department investigators are assisting with the case and they believe that an accelerant was used to light the victim on fire.
The family has told police that the couple had an on-again, off-again tumultuous relationship that was complicated by financial trouble. They had been known to fight and had been involved in several domestic disturbances.
"This is a thought out process. This didn't happen, in our opinion, due to a sudden quarrel or heat of passion," Crump said. "This was thought out and this was planned and this was an act which he intended to inflict upon her."
While police believe Robinson planned to kill Hall, they also said the exact motive is not clear yet.
In addition to his child with Hall, Robinson reportedly has at least two children living in another state.
Robinson, who has a history of property crimes, denied being involved in the homicide when investigators interviewed him.