Authorities in Maryland were no closer Monday morning to finding the sniper who killed six people in 24 hours last week, and one police official openly worried that more shootings would come.
"Clearly, we are at a level of anxiety," said Montgomery County Police Chief Charles Moose. "The rush hour, the number of people who come out on a Monday morning certainly tells us it's an enhanced target-rich environment."
A "geographical profiler" was brought in from Canada over the weekend to apply recently developed methods to determine where the killer probably lives, and the FBI was working on a standard psychological profile as well.
Kim Rossmo, director of research for the Police Foundation, a nonprofit research organization, will analyze the evidence from the shootings to see "if there is a pattern there," he explained. "If we can understand the pattern, we can decode it."
If a series of rapes, for example, occurs over a 10-square-mile area, geographic profiling can often narrow the area in which the attacker is likely to live to within half a square mile, Rossmo said.
Prem Kumar Walekar, 54, an Indian-born taxi driver, on Sunday became the first shooting victim to be buried.
"There's one bad man, but there's so many good people who are showing their blessings and prayer," his sister-in-law Saroj Isaac.
Nephews, nieces and cousins spoke to hundreds of mourners at the Takoma Park funeral, recalling the quiet, hard-working man they will remember as "Prem Uncle."
Sarah Ramos, a 34-year-old woman slain while sitting on a Post Office bench, was to be laid to rest Monday morning in a private service in Silver Spring among members of her family.
Lori Ann Lewis-Rivera, a 25-year-old nanny shot while vacuuming her van at a service station, was to have a wake Monday in Silver Spring before her body was flown back to her native Idaho.
Investigators said Sunday they had thousands of tips, but they conceded it would take time to track down who is responsible for the attacks.
Moose said investigators were making progress, but added, "Some of the more desirable smoking gun leads just aren't there."
Tests conducted by the Bureau of Alcohol, Tobacco and Firearms confirmed that the same weapon -- most likely a high-powered assault or hunting rifle firing .223-caliber military-standard bullets -- was used to kill Walekar and three other victims.
The five victims in the Washington suburbs were gunned down in broad daylight in public places: two at gas stations, one outside a grocery, another outside a post office and the fifth as he mowed the grass at an auto dealership.
The sixth victim, a 72-year-old pedestrian in Washington, was shot to death Thursday as he stood on a street corner.
Each victim was shot once from a distance. There were no known witnesses to the killings.
Investigators said Saturday that ballistics evidence also linked the Maryland murders with the shooting of a 43-year-old woman in Spotsylvania County, Va., on Friday. She was shot in the back in a parking lot at a Michaels craft store in Fredericksburg, Va.
She was in fair condition late Sunday at INOVA Fairfax Hospital.
A window of a Michaels store in Montgomery County was shot out 45 minutes before the first killing, but ATF agent Michael Bouchard said Sunday that a bullet obtained from that scene was too badly damaged to be of any use in the investigation.
Moose said Sunday he suspects all the shootings are linked.
Montgomery County Executive Doug Duncan appealed to residents to continue calling police with any information that might be helpful. About 4,500 calls so far have led to more than 950 credible leads.
Duncan said schools would operate on a normal schedule Monday and outdoor activities would be held. The county executive said he spoke with the pastor at Sunday's funeral for Walekar, who told him he purposely went to the supermarket where one of the shootings occurred.
"He said 'I didn't do it because I wanted to be courageous. I wanted to take back what evil has taken away,'" Duncan said.
The Associated Press contributed to this report.