(NewsNation) — A Georgia boy who went missing last week is now presumed dead, police said.

Authorities have been searching for Quinton Simon since he disappeared Oct. 5 in Savannah. The Chatham County Police Department on Wednesday sent a team of search dogs into his home.

“We are saddened to report that CCPD and the FBI have notified Quinton Simon’s family that we believe he is deceased,” the police department tweeted Wednesday night. “We have named his mother, Leilani Simon, as the prime suspect in his disappearance and death. But, no arrests have been made and no charges have been filed.”

The police department will hold a news conference Thursday to release more details.

“We know that thousands of people around the world will be heartbroken by this news, and we share your sorrow,” the department said.

Law enforcement announced Tuesday that they were officially treating the case as a criminal investigation and they had “seized evidence” they believed would “help move the case forward.”

Meanwhile, reports say tensions rose between Simon’s grandmother, Billie Jo Howell, and his babysitter, Diana McCarta.

Footage obtained by NewsNation’s local affiliate WSAV shows a heated exchange between Howell and McCarta after McCarta reportedly suggested creating a memorial for the missing 20-month-old child.

“My baby’s not dead,” Howell can be heard yelling on video recorded by McCarta’s daughter.

Howell had custody of Simon at the time of his disappearance from her house, where her daughter and her daughter’s boyfriend were living. Simon was last seen at the house by the boyfriend, according to police.

It wasn’t until after Simon’s mother woke up that she reported the boy missing.

NewsNation reporter Joshua Eferighe contributed to this report.