CHICAGO (CBS) — An Elgin man has been charged with killing his elderly mother, dismembering her body, and dumping it in Chicago. Parts of her body were believed to have been found in the Lincoln Park lagoon.

Brian Peck, 55, has been charged with first-degree murder and concealment of a homicide in the death of his mother, 76-year-old Gail Peck, according to Elgin Police and the Cook County State’s Attorney’s office.

At a bond hearing Tuesday afternoon in Rolling Meadows, Cook County prosecutors said Brian Peck admitted to killing his mother, and then putting her body in a bathtub, and hacking it up. He was ordered held without bail at a bond hearing Tuesday afternoon in Rolling Meadows.

On murder of Gail Peck, in court prosecutor says Brian Peck told investigators "I put her in the bathtub & hacked her up." @cbschicago pic.twitter.com/eYGft3C1sr — Mai Martinez (@MaiReports) October 31, 2017

Brian Peck reported his mother missing on Friday, telling police she left home to walk her dog, and then the dog came back alone. Elgin police said further investigation revealed “Gail Peck’s disappearance may not have occurred as reported.”

On Saturday, a fisherman found human remains and a hand saw in a duffel bag in the South Lagoon at Lincoln Park, and called 911, according to police and prosecutors. Police divers and detectives went to the scene, and found another bag with more remains from the same body.

The remains included the torso and parts of two legs of a white woman who had a scar on her back from surgery. The victim remained unidentified as of Tuesday morning, but an autopsy determined the scar was consistent with a spinal fusion surgery, and prosecutors said in court that Gail Peck had spinal fusion surgery. The Cook County Medical Examiner’s office was waiting for the results of DNA testing to confirm their findings.

Prosecutors said police have evidence of Brian Peck withdrawing $500 from his mother’s checking account at a drive-through ATM two days before she was reported missing, hours after her last contact with anyone but her son. About a half hour later, Brian Peck was caught on video buying carpet cleaner and Oxyclean at Walmart. A few hours later, he called their cleaning woman, and told her not to come that day. The same afternoon, he was caught on video buying bricks, tarps, and nylon cord at Home Depot.

The next day, Brian Peck allegedly bought a 5-piece luggage set, a duffel bag, and a steam cleaner at Home Depot. The luggage and duffel bag were identical to those that contained the body parts discovered in the Lincoln Park lagoon and pieces found in a closet at the Pecks’ home.

A red towel in the suitcase that contained a torso matched towels found in the Peck’s home, and a cadaver dog alerted to human remains in the trunk of Gail Peck’s car, according to prosecutors.

Prosecutors said, after Gail Peck was reported missing, police discovered a blood stain on the carpet of her bedroom, and a bottle of carpet cleaner nearby. A larger blood stain had soaked into the wood floor beneath the carpet, and into the ceiling tile of the basement below. More blood stains also were found on an armchair, a table, a washing machine, a sink, and the steam cleaner Brian Peck had purchased the day before.

When police confronted Brian Peck with the video evidence from the stores, and the luggage containing the body parts, he allegedly told investigators his mother had been complaining Wednesday morning about him playing loud music at 3:30 a.m., and told him to leave. He allegedly admitted he then knocked her leg out from under her, and stomped on her head and neck, and realized she was dead, so he put her body in a bathtub and hacked her up.

Brian Peck allegedly confessed to dumping his mother’s head and arms into Montrose Harbor in Chicago on Wednesday, and tossed the rest of her body in the Lincoln Park lagoon on Thursday.

Brian Peck previously was charged with domestic battery in 2016, after allegedly striking his mother in the face during an argument, threatening to kill her, and picking her up by the neck and choking her.

He also has previous convictions for identity theft, aggravated battery, computer fraud, possession of a stolen motor vehicle, and theft by deception, according to prosecutors.