Human remains found last week in a Georgia landfill were those of missing 20-month-old Quinton Simon, the FBI said Monday.

The human remains found in the Superior Landfill in Savannah, Georgia, on Nov. 18, were confirmed through DNA analysis to be from Simon, who was reported missing Oct. 5 in Georgia, authorities said. 

Following the initial discovery of the remains, police on Nov. 21 arrested Quinton’s mother, Leilani Simon, 22, on charges of malice murder, concealing the death of another person, false reporting and making false statements involving her son. 

Following her arrest, Police Chief Jeff Hadley told reporters at a news conference that Simon had been the sole suspect since the child was first reported missing.

“This is a heartbreaking development,” Hadley said. “From the beginning, we were hopeful we would find him alive and unharmed. But evidence has always pointed to the mother and we believe his remains were found in the landfill.”

The FBI thanked the Chatham County Police Department for their assistance in the five-week search for Quinton, saying “a monumental team effort was put forth by everyone involved in bringing closure to this horrific situation.”

During the search, officers combed through 1.2 million pounds of trash over a 30-day period. Police added that the FBI says landfill searches are only successful 5% of the time.

The Chatham County District Attorney’s Office is now handling the case against Quinton’s mother, the FBI said.