Jesus Castillo-Dimas was charged with first-degree intentional homicide in the death of his 2-year-old son.
The 22-year-old man also was charged with three counts of attempted homicide involving domestic abuse and use of a dangerous weapon.
He could serve life in prison if convicted.
In court Friday, Assistant District Attorney Mary Ellen Karst explained why bail was set at $250,000 per charge.
"What I would not want to see happen here is for cash bail to be posted and (Immigration and Customs Enforcement) then to be able to remove (Castillo-Dimas) from this country without us being able to complete a prosecution of this matter," Karst said.
Castillo-Dimas signed off to get a lawyer in Dance County Circuit Court Friday, which the judge said he'd need next week when he returns July 19 for a preliminary hearing.
The judge also ruled Castillo-Dimas cannot have contact with the two victims in this case, if he is able to post the $1 million bail.
According to a criminal complaint, Fitchburg officers arrived to the area of Red Arrow Trail and Thurston Lane about 1:10 p.m. on Monday to find a young child underneath an SUV.
Officers said it was clear the child, 2-year-old Yandel Castillo-Castillo, was already dead at that time and officers "could see brain matter on the parking lot," according to the criminal complaint.
Officers said a man was pinning down Castillo-Dimas and there was a woman, Maria Castillo-Castillo, crying next to the SUV. Miguel Menedez-Ruvalcaba was the man pinning Castillo-Dimas down and he told police he was Castillo-Castillo's new boyfriend. He told police Castillo-Dimas had been following them.
"Maria asked him to drop her and her son off in the driveway where the incident occurred, that way Jesus could not follow her with his vehicle," stated the criminal complaint. Castillo-Castillo and Castillo-Dimas had a confrontation about her new relationship.
"Maria and (Yandel) were holding hands walking toward their apartment, and as (Yandel) was saying 'Pa, Pa, Pa. Pa", (Miguel) observed Jesus drive forward and run over his own son," stated the complaint.
Menedez-Ruvalcaba said Castillo-Castillo was thrown backwards, too. He told police he "watched in shock as Jesus put his vehicle in reverse and once again ran over his own son who was lying dead underneath the vehicle," stated the complaint.
The complaint said Castillo-Dimas then got out of his vehicle, pulled out a knife and walked over to Castillo-Castillo yelling repeatedly, "I'm going to kill you." Castillo-Castillo suffered several stab wounds, including one close to an artery in her neck.
The complaint said Menedez-Ruvalcaba ran at Castillo-Dimas and tried to take the knife away. Menedez-Ruvalcaba was cut deeply on the hand and the two men fell to the ground. Menedez-Ruvalcaba was stabbed twice in the stomach area, but was able to get the knife out of Castillo-Dimas' hands.
Menedez-Ruvalcaba detained Castillo-Dimas until police arrived. Castillo-Castillo told officers on Wednesday that Castillo-Dimas was laughing during the incident and said "Neither of the two of us are going to have him."
The couple had broken up about six weeks before this incident, after being together for five years. She told police Castillo-Dimas had been calling her constantly since the break-up, including 32 times in the previous 24 hours.
Detailed accounts from the two victims released Friday said Castillo-Dimas told his ex-girlfriend, "There's nothing you can do now. Neither of us are going to have (our son) now," while he was attacking her.