The last time friends and family saw Hector Nieves and Luis Garcia, they were drinking and singing songs to mark the start of the annual festival of a local patron saint.

At dawn the next morning, as they pulled into the nearby town of Palmarito to continue the celebration, they were shot dead by gunmen in an attack that killed at least four.

Police have no leads because no witnesses came forward, but residents of the border area including in Guasdualito, a city of 60,000 residents 25 km (15.5 miles) from the Colombian border, have suspicions about who was behind the killings.

"We've become a victim of the violence of illegal Colombian groups," said 56-year-old Aldo Marquez, the historian of Guasdualito, in reference to the February attack.

Venezuela has resolved its dispute with Colombia that sparked the Andes' worst diplomatic crisis in a decade earlier this month, but violence from Colombia's 40-year-old conflict is still hitting Venezuelans living in border regions.

Authorities and rights groups speak of alarming incidence of kidnappings, extortion and executions due to the presence of leftist guerrillas who have moved across the border due to a lack of state presence in the isolated region.

The situation may create problems for leftist President Hugo Chavez, who has expressed sympathy for FARC guerrillas and is fending off charges he supports them.

Colombia accused Caracas and Quito of backing the FARC guerrillas based on documents in computers they found during a raid inside Ecuador that killed a top rebel commander and triggered the recent diplomatic crisis.

Though guerrillas have operated in Venezuela for decades, the problem has worsened in recent years, residents say, although there are few statistics.

Guasdualito Mayor Jorge Rodriguez, himself a Chavez supporter, in a recent newspaper interview said Colombian guerrillas are responsible for the growth in hit-man style killings often carried out in broad daylight.

"We have suffered a continuous onslaught of FARC and ELN on the border," Rodriguez said, referring to Colombia's principal guerrilla groups.

Residents speak of a shadowy Venezuelan armed group called the Bolivarian Liberation Forces that is accused of murder and kidnapping but does not have a visible leadership. Although it is Venezuelan, its methods are similar to the Colombians'.

Right-wing paramilitary groups commit similar crimes in the states of Zulia and Tachira to the northeast of Guasdualito, relief groups say.

"We live oppressed by these criminal groups," said a group of 180 Guasdualito residents in an unusually candid January statement denouncing the persistent violence.

CLIMATE OF INTIMIDATION

Victims of the violence do not openly discuss the problem because of a climate of fear and intimidation.

"You could watch your brother get shot and you would say you did not see anything," said one detective who asked not to be identified.

He said he witnessed an execution within blocks of the investigative police headquarters while drinking a beer after work, firing shots in vain at the assassin who fled the scene.

Lawlessness and limited state presence have become a reality on the sparsely populated 1,400 mile (2,200 km) border. The terrain includes isolated mountain ranges and vast plains, like those surrounding Guasdualito, that flood during the rainy season.

Official figures show at least 47 murders since October in Guasdualito, but authorities recognize the actual toll is likely much higher.

Many said they know the identity of the hit-men, who often shoot at victims in public while riding motorcycles but do not speak out for fear of reprisals.

One relief agency worker who asked not to be identified said the execution-style killings were initially linked to guerrilla clashes but are now used to resolve anything from commercial disputes to accusations of infidelity.

"It has become a way for people to settle differences," he said.

Guerrillas for years charged extortion fees to ranchers but the practice is now so pervasive that it is applied to even small-time merchants and informal streets vendors, the detective said.

More than half of Venezuela's 249 kidnappings last year were in border states, according to local media.

Despite Chavez's insistence that guerrillas are not involved in kidnapping, authorities say common delinquents often capture hostages and later sell them to guerrillas.

Colombian President Alvaro Uribe's U.S.-backed military campaign helped isolate the FARC in Colombia but has also pushed guerrillas into new territory, increasing combat between rival armed groups that has spilled into Venezuela.

Guasdualito historian Marquez says the violence has turned the peaceful town he knew as a child into a place where people are afraid to walk the streets at night.

"I would prefer to live in a Guasdualito with no electricity, no water and no phones than to live in a Guasdualito with this level of violence," he said.