The motive for the murder of Jennifer Hudson's family could be plain ol' -- but deadly -- jealousy, according to prosecutors.

William Balfour, they allege, warned estranged wife Julia Hudson, Jennifer's sister, he would "harm" her family if she continued to see a new man. Balfour confronted them, they say, on the day of the murders.
We're told Balfour was just brought in to Cook County Jail and booked after his bond hearing today, and is being housed in the general population.
Just a few hours ago, his bail was denied.

Looks like William Balfour really isn't going anywhere anytime soon, as a judge just denied him bail at a hearing in Chicago.
Prosecutors revealed they found gunshot residue on the steering wheel of the car Balfour drove to the Hudson house. They also presented evidence that refuted several of Balfour's alibis, including his location at the time of the murders and his use of the subway to get to the Hudson house.
Balfour's lawyer still argued for bail on the grounds the state's evidence is largely circumstantial.
He was charged yesterday with three counts of first-degree murder and one count of home invasion.
Story developing ...

The Cook County state's attorney's office has just officially charged William Balfour with the murders of Jennifer Hudson's mother, brother and nephew.
He's been charged with three counts of first degree murder and one count of home invasion.
Balfour is scheduled for a bond hearing at noon Central time tomorrow.
UPDATE 4:21 ET: In their presser, which just ended, the State's Attorney and cops said they're "confident" about their case, which some unnamed sources have claimed is "mainly circumstantial." They said they do have physical evidence tying Balfour to the scene, and emphasized they did not cut a deal with Balfour's girlfriend to elicit her testimony.

Chicago cops have arrested William Balfour for the murders of Jennifer Hudson's mom, brother, and nephew.
Balfour was transferred to CPD custody today after they served an arrest warrant. Charges from the Cook County State's Attorney's Office are pending.
UPDATE: We're told the CPD had no new evidence against Balfour -- but they were finally able to scrape all the dirt on him into one pile, which was enough to make the arrest. Also, Balfour is still waiting to be formally charged -- and this could take a day, or up to a week.
Story developing ...

More Today in TMZ History

William Balfour called a Mississippi college student the morning of the Hudson triple murder -- so she says -- and asked if he and his "boys" could stay with her after doing "something real big" in Chicago that day.
Rashia Whitlock told investigators Balfour called her at 4:00 AM on October 24, the day the murders occurred, and, according to the Chicago Sun-Times, told her he and his "boys" were "getting ready for something real big that's going to go down tomorrow." Balfour then asked if they could come visit her, says Whitlock, which she refused.
Whitlock also said Balfour asked her whether she knew Jennifer Hudson and, more ominously, if Whitlock could be "loyal." She said she had met Balfour on MySpace.
William Balfour is flat out denying any involvement with the Hudson family triple murders -- and in today's parole hearing, officials say Balfour seemed "disturbed" by his girlfriend's accusation she saw him with a gun similar to the murder weapon.

According to Illinois Prisoner Review Board Chairman Jorge Montes, Balfour will remain in jail until at least December 3. The decision was based on the alleged gun connection
as well as probable cause on a number of other alleged parole violations.

The parole hearing for William Balfour, the main suspect in the Hudson family killings has ended, and he will remain in jail at least until December.
We're told the key evidence against Balfour came from a former girlfriend, who said she saw him with a gun that appeared to match the murder weapon. He will have another hearing on December 3.
The parole board did not make its decision because of the murders, although it's curious why it mentioned the weapon.
The board also said it made its decision because he was in a place where drugs were sold.
Balfour has been in custody since October 24.

William Balfour -- the only suspect in the Hudson triple murder case -- allegedly told his current girlfriend he was involved in the murders of Hudson's mother and brother, according to sources at the Chicago Tribune.
Balfour's girlfriend in turn told police what he told her. The Tribune
also cites sources saying Balfour "acknowledged being at Hudson's Englewood home" on the morning Jennifer Hudson's mother and brother were shot to death inside, and Jen's nephew was abducted and later killed.
These are incredible statements considering William -- who has not been charged with a crime -- could be released tomorrow morning pending a decision by the Illinois Prisoner Review Board on whether he violated the terms of his parole.
Chicago police refused to comment.

Monday morning could be absolutely huge in the Hudson family murder case -- the cops' only suspect, William Balfour, could walk out of jail a free man.
Law enforcement sources tell TMZ Balfour, who's only being held on a parole violation in a case unrelated to the murders, could "conceivably" skate if there's not enough evidence to prove he did violate his parole. He's scheduled to face the Illinois State Parole Review Board Monday at 9:00 AM.
The only way authorities could keep Balfour in custody is if they officially charge him for the Hudson killings between now and Monday, or if they find that he
did violate his parole
Thus far, no other suspect has been named in the triple murder of Jennifer Hudson's mother, brother, and nephew.
Two weeks to the day after her mother, brother, and son were brutally murdered, it's hard not to point out what Jennifer Hudson's sister Julia is saying with words and pictures on her MySpace page.

Most bewildering is this: Under one picture Julia writes, "NOW THAT JASON'S GONE I'M THE PRETTIEST ONE," an apparent reference to brother Jason, whose body was found shot to death along with their mother's.
Other photos show her partying with friends.
Julia has taken down pictures of William Balfour, her estranged husband and still the only suspect in the case.

One of the victims in the Hudson murder case could have been shot to death by his own weapon.
Jennifer Hudson's brother Jason owned a gun that may have been identical to the murder weapon, according to law enforcement sources and neighbors who spoke with the Chicago Tribune.
According to those sources, Jason said the gun had been stolen from the family home -- the crime scene -- a few months ago.
Law enforcement sources are now investigating whether the gun used in the Hudson triple murders once belonged to Jason Hudson.
Jason's brother-in-law, William Balfour is the suspect in the case.