BAY CITY, Mich. (Detroit Free Press) -- Weeks before a 4-year-old Mt. Pleasant boy was found dead under a porch, his mother's boyfriend had been physically abusing him and once left him with a bruised and swollen face, according to an FBI affidavit unsealed today.

The affidavit offered detailed accounts of at least three alleged assaults on the boy by his mom's boyfriend, Anthony Bennett, who was charged today in federal court with assaulting - but not killing - 4-year-old Carnel Chamberlain. Per the affidavit, it was Carnel's mother, Jaimee Chamberlain, who disclosed to a federal agent that her boyfriend had assaulted her son three times in the weeks before the boy's June 21 disappearance.

The affidavit did not say whether Jaimee Chamberlain ever reported the alleged abuse to authorities.

Here, according to her interview with an FBI agent, is what happened to her son.

It was late May or early June when Jaimee Chamberlain came home from work and her boyfriend Anthony Bennett, who lived with her, asked her to sit down. He asked her to tell him that she loved him. What came next was disturbing.

Jaimee Chamberlain entered a bedroom where she saw her son on a bed with a bruised and swollen face, and a cut on the inside of his lip. A few days after this incident, the mother observed a 6- to 8-inch-long bruise along the boy's ribcage. Bennett, the boyfriend, informed the mother that he had backhanded Carnel, who subsequently told his mom that Bennett had punched him. This all took place in the boy's home on the Saginaw Chippewa Indian Tribe reservation, where the mom, boyfriend and son lived.

A few days after that incident, another assault took place. This time, the mom witnessed it. She saw Bennett pick Carnel up by his neck, drop him, and then drag him by his right foot to his bedroom, which bruised his buttocks.

"Based on the above information, probable cause exists to believe that Anthony Bennett, an Indian, assaulted Carnel Chamberlain, a child under 16 years old, within Indian country," FBI agent Steven Flattery wrote in the affidavit.

Bennett reportedly had consulted with an attorney after Carnel was reported missing, but no lawyer is on record in the case.

Hundreds of people, including Carnel's mother, gathered Thursday night at a vigil for Carnel near Mt. Pleasant at the Saginaw Chippewa Indian Tribe's reservation. He was reported missing June 21 while in the care of Bennett, when his mother was at work.

For days, investigators searched woods, ponds and the tribe's wastewater treatment areas to no avail.

"Nothing this monumentally horrific has ever happened in our community," said family spokesman Kevin Chamberlain, who grew up on the reservation and served as tribal chief from 1997 to 1999, of Carnel's death. He is Jaimee Chamberlain's cousin. "Right now, it's a very somber place with a lot of broken hearts."

The case is being prosecuted by the U.S. Attorneys office, which has jurisdiction over certain crimes on Indian lands.

Bennett made an initial appearance in U.S. District Court in Bay City today. He is temporarily jailed pending a detention hearing, and is awaiting a court-appointed attorney to be assigned to his case.

By Tresa Baldas, Detroit Free Press Staff Writer