When soldiers of Nigeria's corrupt and incompetent army patrol remote and vulnerable towns in the northeast, boys often watch as they pass, then hurl rocks at them.
Yet early last month, residents of Gamboru Ngala, on the border with Cameroon, cheered the uniformed men on military vehicles who drove into town around lunchtime on market day. It looked as though the army, sent off earlier that day to help rescue more than 200 missing schoolgirls abducted by Boko Haram militants, had won a victory worth celebrating.
"People came out shouting and cheering and hailing them," said Abba Adam, 42, a market trader. But the cheers soon died out. The uniforms weren't quite right: baggy trousers here, a caftan there, a couple of turbans.
"That was when we realized that they weren't soldiers," said Ali Malallam, 32, a cellphone repairman who had just finished midday prayers.
The carnage was staggering. By the next morning, authorities had counted 315 bodies, many of the victims shot to death in the market, and 17 police officers killed at their headquarters. The officers were shot with AK-47s fired from SUVs, motorcycles and three armored personnel carriers. Just before they opened fire, the Islamic militants unfurled a black flag and yelled, "God is great!"
Now many in the Muslim northeast, already largely supportive of the opposition to President Goodluck Jonathan, wonder whether the army has been conspiring with Boko Haram to breed instability and commit genocide.
The local reaction reflects a legacy of distrust that helps explain why it has been so difficult for Nigeria to battle the insurgents. The country struggles with long-standing animosity between the north, which is largely Muslim, and the Christian-dominated south. Its army has a reputation for brutality, neglect and failure. Those problems hamper the type of close cooperation between the military and civilian population that is essential to a successful counterinsurgency.
The conspiracy theories run rife in northeastern Nigeria, no matter how wild. Rightly or wrongly, many see the military's refusal to intervene after warnings of impending attack or during assaults as suspicious. Why, they ask, have there been so many attacks on villages just hours or a day after the military left?
Meanwhile, the president's supporters, including prominent politicians in the south, are airing similar conspiracy theories, accusing northern governors opposed to Jonathan of funneling support to Boko Haram to make the country ungovernable for him in the run-up to elections next year. Such political, regional and sectarian strains unleashed by the Boko Haram insurgency are ripping at Nigeria's frayed seams, threatening to pull the fragile country apart.
This month, Nigerian news reports said that 10 generals and 15 senior officers had been convicted of treason for giving information and ammunition to Boko Haram, although military headquarters denied the reports.
Gamboru Ngala is a major trading hub with a population of about 240,000. The attack there took place on a day when hundreds of traders were in town, some from nearby Cameroon and Chad.
Boko Haram's latest tactic is to invade towns, pretending to be members of the military, order village men to gather in a central location, and then open fire.
"They invaded the town, burning and shooting and setting off bombs," Adam, the trader, said by phone. "There was panic and everyone was running for safety.
"After the shots, we heard huge explosions of RPGs [rocket-propelled grenades] and heavy machine guns. We were petrified. If they saw someone running into a house to try to escape, they'd shoot them and burn the house."
Attacks apparently carried out by Boko Haram insurgents disguised as soldiers are increasingly common in Nigeria, with invasions of three northern villages, according to news reports. The gunmen are said to have invaded Danjara, Agapalwa and Antagara, gathering residents in the center of town and then opening fire, killing 200 people.
In Gamboru Ngala, the gunmen blasted the market shops with heavy weaponry and set them on fire, incinerating dozens of people inside, witnesses said.
"We just ran to the back of the market and started running home," said Malallam, the cellphone repairman. "When we got to the police station, we saw these guys with APCs [armored personnel carriers] and heavy weapons. We just turned back because they were shooting.
"From there we were just playing cat and mouse. We'd run into an alley; then you'd see two of them coming and you'd have to run the other way. We ran in and out of alleys until we managed to get out and across the border into Cameroon," he said.
Many people fled to the town of Fotokol, just across the border in Cameroon. But Malallam's wife, Fatima, was trapped. She had been delivering party invitations, leaving her four children, ages 1 to 7, at home.
"She ran towards home to get to our children, but she ran into these people on APCs. They were setting fire to cars and shops and at one explosion, she passed out from the heat. Luckily a woman dragged her into a nearby house," her husband said.