SAN ANTONIO, Texas - A body has been found in the search for a missing 8-month-old boy after police said his abduction was staged by his family, according to an affidavit obtained by CBS affiliate KENS

San Antonio Police Chief William McManus said the father, grandmother and cousin of King Jay Davila have been charged in the case. All are in custody on evidence tampering charges. Police said Thursday the child is believed to be dead.

According to the affidavit obtained by KENS, the baby's father, Christopher Davila, allegedly led investigators to an open field where a child's body was found wrapped in a blanket inside of a black backpack. Davila, who denied involvement in the child's disappearance, is charged with child endangerment.

The affidavit says Davila, 34, told police he was playing video games Jan. 3 while the child was in a car seat on a bed in his room, reports the San Antonio News Express. Davila claimed the car seat fell over, and the boy fell to the floor and possibly hit his head on a dresser. Davila said he didn't seek medical attention, but waited for several hours, and then checked on the boy and found him dead.

At a Thursday night news conference, McManus said Davila is believed to have injured the child severely, then told police the boy was in a car that was stolen Jan. 4. McManus said the child's grandmother,Beatrice Sampayo, is suspected of disposing of the child's car seat and dropping off Angie Torres, the child's cousin, who was seen on surveillance video driving away in the car from a gas station, allegedly participating in a staged kidnapping.

Three male witnesses who remain unidentified are currently speaking with police, KENS reports.