BISBEE — Cochise County Sheriff Larry Dever called the Saturday slaying of longtime rancher Robert Krentz a "senseless shooting" by a "sick and sorry" person and said there is no evidence to suggest there was any confrontation that led to the shooting. 

Krentz, who was out checking water line and fencing on his family's 35,000-acre ranch, had weapons with him in the ATV Polaris but he did not use them, Dever said.

Investigators have determined the shooting was carried out by one person but don't know anything about who it was, including if it was a man or woman. They believe it was an illegal immigrant because Krentz was heard telling his brother on the radio "illegal alien" and because the area is a known smuggling corridor.

They have no motive.

"There is absolutely no reason this had to happen other than the bad intentions of one sick, sorry individual that we hope to be able to catch up to very quickly," Dever said.

Dever said Krentz was frustrated and fed up with the illegal activity like many ranchers in the area. But he said he was compassionate and regularly helped illegal immigrants in distress.

"There is no reason to believe anything else other than that happened that day with Rob," said Dever, who added that his interest was likely to check on the shooter's welfare.

Robert Krentz was found about 1,000 feet from where they believe the shooting occurred, dead in his ATV. The ATV still had its lights on and the engine running, Dever said. There were spin out marks in the dirt, leading investigators to believe that he was trying to get away from the shooter, Dever said.

Investigators believe the shooter was headed south toward the border when Krentz encountered him. Law enforcement tracked a single set of footprints — believed to be the shooter's — for 20 miles to the U.S.-Mexico border. They also contacted Mexican authorities but so far there is no information about the suspect.

"We are assuming he escaped south into Mexico," Dever said.

Dever admitted it will be very difficult to find the shooter, and would likely require that the shooter talk about the incident with somebody.

While investigators don't have a motive yet, retaliation has been raised as a possibility, Dever said. The day before the shooting, the victim's brother, Phil Krentz, reported drug smuggling activity on the ranch to the Border Patrol.

Agents found 290 pounds of marijuana on the ranch and followed tracks to where they found and arrested eight illegal immigrants, said Border Patrol Tucson Sector deputy chief Robert Boatright. None were prosecuted because of a lack of evidence.  They were all in custody when the shooting occurred, he said.

Krentz regularly called the Border Patrol to let them know about illegal activity on the ranch, the agency said.

Dever also said there was another incident within 24 hours of the shooting that could be connected involving a gun, but he would not elaborate.

The area where the shooting occurred is a well-known drug and people smuggling corridor, Boatright said. In the summer of 2009, after seeing a spike in activity in the area, the agency opened a base staffed around the clock with 20 agents.

Dever said his deputies have responded to numerous calls from residents in the area about burglaries, property damage and even a few home invasions. Recently, the county had assigned all of the deputies working overtime hours under the Department of Homeland Security's Operation Stonegarden grant program to the area.

"There has been a prevailing sense for sometime in the community that something like this was going to happen," Dever said.

The shooting has sent a chill through county, and particularly among ranchers in the Portal/Apache area, Dever said.

"Rob Krentz was a good friend of mine. The entire family, the ranching community and all of Cochise County is deeply impacted by this horrific event," Dever said. "They are deeply saddened by the loss of a good man."

Wendy Glenn, who lives on the neighboring Malpai Ranch, said she heard Krentz radio to his brother Sunday morning on a radio network used by area residents.

“He said ‘There’s an illegal here that needs help’ and ‘I’m out at such and such windmill’ and ‘Please call the Border Patrol,’” Glenn said. “His brother said ‘I can’t hear you.’ ”

In that area, most ranchers use All Terrain Vehicles to check water supplies, fences, cattle and do other jobs on the ranch, Glenn said.

The Krentz brothers’ conversation was routine for the area between the New Mexico border and the Chiricahua Mountains, which has been an active corridor for border crossers, she said.

Agents from the Border Patrol’s El Paso sector have helped in the area, but they have difficulty communicating with the agents from the Douglas station because of differences in their radio systems, Glenn said.

Krentz was a member of the board of the directors of the Malpai Borderlands Group, an organization of conservation-minded ranchers. The Krentzes also had a conservation easement on the family’s land, meaning the land can’t be subdivided.

“They really believe that if you take care of what’s out here, it will take care of you,” Glenn said.

Krentz’s family had been ranching their property since 1907, and in 2008 the Krentz Ranch was inducted into the Arizona Farming and Ranching Hall of Fame.