San Antonio Police said they believe the missing eight-month-old boy, King Jay Davila, was dead. In this representational photo, a handcuffed inmate meets with an attorney to update his case in the overcrowded Puraquequara prison in Manaus, Brazil, Feb. 18, 2016. Getty Images/ Mario Tama

San Antonio Police said at a press conference Thursday night that they believe the missing eight-month-old boy, King Jay Davila, was dead.

Davila, who was last seen on Jan. 4 around 7 p.m. local time (8 p.m. EST), initially believed to have been kidnapped, was never found. In a press conference, San Antonio Police Chief William McManus said the department had brought evidence tampering charges against the boy’s father, Christopher Davila; the boy’s grandmother, Beatrice Sampayo; and another family member, Angie Torres, who already was in jail on an unrelated charge.

“Angie Torres heard from Beatrice that Christopher had severely injured King Jay,” McManus said, NBC-affiliated News4SanAntonio reported. “Statements from multiple witnesses unfortunately lead us to believe that King Jay is dead.”

Christopher was charged with child endangerment in connection with the infant's disappearance and is currently out on bail. Police believe Torres hatched a plan to stage a kidnapping after finding out what King Jay’s father had done.

On the night that the child went missing, Sampayo dropped off Torres a block from a gas station in the 300 block of Enrique M. Barrera Parkway, San Antonio, California, where Christopher parked his car and went into a convenience store to make a purchase. He had left his car unlocked and running supposedly with King Jay inside it, making it easy for Torres to steal his car and drive off with the infant.

King Jay’s mother, Jasmine Gonzales, later told the police she was on a call with Christopher at the moment he discovered that someone had stolen his car with the infant in it.

“He was, like, ‘F---, the car is gone!’ He freaked out and I was, like, ‘OK, hang up and call the cops!’ He did just that. He hung up on me and at that time I called the cops, too," Gonzales said, ABC-affiliated KSAT reported. “They said they already sent two policemen there, and then all of a sudden they started accusing him.”

The car was eventually located by the police abandoned near Rodriguez Park without the keys or King Jay's car seat inside. However, investigators believe that King Jay was never inside the car when it was stolen and the fake car theft and abduction were acted out to cover up the infant’s murder.

"We believe that the story of the kidnapping was made up, made up to cover up foul play involving King Jay Davila," McManus said Monday night. “Ask yourself why would someone concoct such a story.”

However, McManus stressed on the fact that the arrests did not signal the end of investigation on the case and that they were still “actively looking for King Jay.”

“Our focus will remain on finding him and I will again tell anyone who has information that your time is running out,” he said. “Come forward and talk to us if you have information about his whereabouts or what happened to him. If you've already lied to us, then, we're going to charge you too."

On Saturday, the San Antonio Police Department announced that the FBI will be joining hands with them to locate the missing infant.

“It’s even more appreciated that these agents are volunteering their time and expertise to help us find King, despite them not being paid during the current government shutdown. Together, we will work tirelessly to find baby King,” McManus said in a prepared statement.