"Thank you all for your prayers and your calls," the blog entry said. "Please keep praying for our family and that we get Julian King back home safely. If anyone has any information about his whereabouts, please contact the authorities immediately. ... Once again, thank you all for being there for us through this tough time."
Hudson announced late Sunday, through her publicist, that she was offering a $100,000 reward for Julian's return.
"Jennifer Hudson and her family are offering a reward of $100,000 for the safe return of her nephew Julian King, who has been missing since Friday, Oct. 24," the statement released by Lisa Kasteler said. "We ask that all inquiries be directed to the Chicago Police Department, Area 1 Detective Division at 312/747-8380. Jennifer and her family appreciate the enormous amount of love, support and prayers they have received while she and her family try to cope with this tragedy and continue the search for Julian."
Julia Hudson, the boy's mother and Jennifer's sister, held a news conference Saturday to plead for her son's safe return.
In the impoverished South Side Chicago neighborhood where the singer and actress grew up and which she often credited for her success, her sister Julia Hudson stood fighting back tears.
"All I ask, I don't care who you are, just let the baby go. Please," Julia Hudson said Saturday before a crowd from the podium of the Pleasant Gift Missionary Baptist Church, where her sister sang as a child. "My biggest fear has already happened. My greatest hope is finding my child."
With Greg King, the boy's father, beside her, Julia Hudson expressed her belief that Julian was still alive and added that her brother's white truck was missing.
"I know he's out there," said Julia Hudson, who discovered the bodies of her mother and brother Friday at the family's Englewood home and soon realized her son was missing. "Just let him go. Put him on the side of the street. He'll sit there. Somebody will see him. He'll probably cry until somebody comes along.
"I just want my son. That's all I have to say. Please just let my baby go. He didn't do nothing to nobody, nobody. He don't deserve this," she said.
Illinois Sen. Barack Obama, who shares the Hudsons' Chicago hometown, issued a statement Saturday:
"Michelle and I were absolutely heartbroken to learn about this unimaginable tragedy, and we want Jennifer to know that she is in our thoughts and prayers during this very difficult time," the Democratic presidential candidate said. "We also pray for the swift and safe return of her young nephew."
Jennifer Hudson sang the national anthem during the Democratic National Convention in August after a personal request from Obama's camp.
Autopsy results released Saturday showed that Jennifer Hudson's mother and her brother died of gunshot wounds, according to the Cook County Medical Examiner's Office. Their deaths were ruled homicides.
While Julia Hudson did not address her relationship with William Balfour, the news media are reporting that Balfour is the "person of interest" who was named in the Amber Alert after Julian's disappearance.
Chicago police have confirmed that they have someone in custody but have not identified the person.
They transferred custody Sunday to state authorities.
No one has been charged in the disappearance or murders.
"From what we know right now, it appears to be some type of domestic situation, but that's very preliminary," Weis said.