The body of an infant, believed to be Justice Rees, was found Wednesday morning.
Investigators had been frantically searching for the boy when his mother, 22-year-old Samantha Green reappeared after being reported missing.
Officials declined to say how the baby died. He was found in the slough by the Yolo County Sheriff's Marine Unit.
About 90 people were involved in the search for Rees, including off-duty law enforcement and firefighters.
Friends and family gathered to pray where the Yolo County Sheriff's Office briefed the media on its investigation.
"(The) baby never had a chance to live," grandfather Randy Green told reporters. "I wish we got to know him better."
Green said his grandson would have been three weeks old Wednesday.
Rowena Shaddox will have the latest on this story on FOX40 News at 5 and 6. Keep checking back on this page as this story develops.