A judge also ordered Jorge Barahona, 53, to undergo a mental health evaluation. He is charged with aggravated child abuse and is expected to face more charges.
On Monday, a state worker found Barahona's son in a truck that was parked along a freeway. The boy was dripping in chemicals so toxic that they sickened rescue workers. His twin sister's deteriorated body was later found in the enclosed bed.
Authorities found Barahona on the ground doused in gasoline. He later told them that he was trying to commit suicide.
The boy is in critical condition. Doctors are not sure what chemical was used.
The Department of Children and Families began investigating the family last week after Barahona's 7-year-old granddaughter told an adult the twins were kept locked in the bathroom.
After the call, a child protective investigator went to the home looking for the twins Friday night, but Carmen Barahona, the suspect's wife, told them she was separated from her husband and didn't know where he or the twins were. Officials now believe she was covering for him.
The Associated Press contributed to this report.