The eighth casualty came Sunday, a day after police discovered seven bodies and two survivors in one mobile home in Brunswick. The latest victim was Michael Toler, 19, who lived in the home and had been hospitalized Saturday. He is the first and only victim police have named.
Police have refused to say how the eight were killed or give a possible motive.
"There's no manhunt, no suspect. Was it a murder-suicide? There's nothing specific they're telling us," the 50-year-old Mugavin said Sunday.
Police acknowledged they don't know if the killer was still out there, urging residents to be aware and cautious.
"The person or persons responsible for this still remain unknown to us," said Glynn County Police Chief Matt Doering, who added the killer could have fled to another county or even another state. "I cannot tell you if they are at large. I simply do not know."
The victims ranged in age from teenagers to adults, with a ninth person hospitalized with critical injuries Sunday in Savannah. Police are offering a $25,000 reward for information, with Doering saying, "We need help."
Police have arrested one man - a family member who lived in the mobile home and called 911 to report the attack, police said. Guy Heinze Jr., 22, faces charges of tampering with evidence, lying to police and illegal possession of prescription drugs and marijuana. He was jailed Sunday.
"He ... came home and discovered (the victims), at least that's what he told us," Doering said.
Asked if Heinze was involved in the slayings, Doering said: "I'm not going to rule him out, but I'm not going to characterize him as a suspect."
The killer was not among the dead or the last survivor, according to Doering.
Earlier, Doering said it was the worst murder case he had ever encountered in his 25 years with the county that includes Brunswick, a city of about 16,000 people between Savannah and Jacksonville, Fla., along Georgia's southeastern coast.
The slayings happened in a dingy mobile home built on the grounds of a historic plantation, nestled among centuries-old, moss-draped oak trees. The park consists of about 100 spaces and is near the center of New Hope Plantation, according to the plantation's Web site.
The 1,100-acre tract is all that remains of a Crown grant made in 1763 to Henry Laurens, who later succeeded John Hancock as president of the Continental Congress in 1777.
The Georgia Bureau of Investigation was conducting autopsies Sunday on four of the victims. GBI spokesman John Bankhead said Glynn County police would be in charge of releasing any results, and Doering refused to comment on them. He said autopsies on the remaining four victims would begin Monday.
Doering defended his vague statements about the case, saying he didn't want the public to know details that might compromise what he called a "tedious" investigation.
Still, the dearth of information has frustrated residents, said Mary Strickland, who owns The Georgia Pig, a popular local barbecue place.
"If it is a murder-suicide then let people know so they don't think there's some lunatic out there," Strickland said. "We got a lot of people who panic and the more information you put out there, the better you make them feel."
Associated Press Writer Dionne Walker in Atlanta contributed to this report.