After gunning down 18 people and wounding 13 more in Lewiston, Maine, on Wednesday night, the man who carried out the rampage apparently fled the small city, disappearing into a forested region that may — for now — help keep him a step ahead of the police.
Hundreds of law enforcement officers are scouring southern Maine for the suspect, Robert R. Card Jr., a 40-year-old Army reservist. The first 36 hours of the manhunt underscored the challenges of finding a fugitive in thickly wooded terrain.
An outdoorsman who has spent years in the military, Mr. Card knows guns and knows the region.
Maine is vast and sparsely populated, with about 1.3 million residents spread across more than 30,000 square miles of forest. The small roads that connect rural towns see little traffic. The state is dotted with campgrounds that by this time of year are no longer filled with summer tourists. Sport hunters will soon be tracking deer with rifles, and it will be common to see armed people in hunting gear and to hear shots fired in the woods.
The search for Mr. Card recalls other difficult manhunts in rural areas, like the long search for Eric Rudolph, the survivalist who set off a bomb in Atlanta during the 1996 Summer Olympics, or the recent hunt for Danelo Cavalcante, the convicted murderer who escaped from a Pennsylvania jail in August.
Mr. Rudolph hid for five years in the North Carolina mountains before being captured in May 2003 and eventually pleading guilty to the Olympics bombing and other crimes. Mr. Cavalcante was at large for 13 days in rural suburbs of Philadelphia before he was captured and sent to one of the state’s most secure prisons.
A look at how such manhunts have been conducted, the technology that searchers can now employ and the realities of Maine’s landscape illustrates both the obstacles that the police face and the advantages that almost inevitably give the authorities the upper hand.
Most fundamental is a fugitive’s need for food and shelter.
“There’s a lot of eyes and ears out there,” said Lenny DePaul, a former fugitive task force commander with the United States Marshals Service. “He’s going to get desperate. He needs provisions. He’s got to eat.”
Mr. Rudolph was spotted by a rookie police officer in Murphy, N.C., as he was foraging for food in a trash container outside a grocery store.
Mr. Cavalcante was spotted stealing a rifle from a suburban garage, giving officials a valuable lead about his location. He was captured two days later after an aircraft lent by the Drug Enforcement Administration to aid in the search detected a heat signal that led the police to a wooded area where Mr. Cavalcante was sleeping.
Indeed, search technology has made significant advances since the 1990s, when Mr. Rudolph was at large. Thermal imaging like that used to locate Mr. Cavalcante can now distinguish between people and animals. Cellphones produce vital tracking data, as long as they are not discarded
But even with night-vision cameras, drones and other modern tools, the law enforcement playbook still relies on assembling a task force of local, state and federal agencies and being ready for the moment when a slip-up by the fugitive or a tip from the community will give the police what they need.
In the Card case, the Maine State Police are leading the search, with help from the F.B.I.; the Bureau of Alcohol, Tobacco, Firearms and Explosives; federal marshals and police departments in Maine, New Hampshire, Massachusetts, and New York.
Once a suspect is identified — as Mr. Card was, almost immediately after the shooting — investigators typically obtain warrants to search the suspect’s home and to obtain records related to him, in an effort to collect clues about where the person might be hiding and to gather evidence for the case prosecutors would be building.
Joyce Vance, a former U.S. attorney in Alabama who worked on the Rudolph prosecution, said that in the case of a man like Mr. Card, with military service and a record of mental health treatment, prosecutors would probably seek warrants for information about his time in uniform, his weapons and his medical history.
They would also be likely to subpoena social media companies for his public posts and private messages, in order to build a psychological profile that could help police come up with an arrest strategy. The suspect’s communications might also reveal whether he acted alone, planned more violence or had a stockpile of weapons.