Hannibal, Mo. ? A Hannibal police officer was finishing up mundane paperwork on a quiet Saturday morning when Manuel Cazares walked into the station, blood splattered on his hands and shoes.

Cazares put his hands out, crossed them, and told the officer to arrest him.

“I killed two people,” he allegedly said.

Details surrounding the allegations are far too common: an abusive relationship, a jilted lover, a sudden attack.

But some in this Mississippi River community of 17,000 best known as Mark Twain’s hometown aren’t just outraged by the violence. They also question why Cazares was in Hannibal at all.

Cazares admitted after his arrest that he is an illegal immigrant from the Mexican state of Michoacan. The 32-year-old had several run-ins with law enforcement before the homicides, but officials had never questioned his legal status.

Now he is charged with two counts of second-degree murder and armed criminal action in the Feb. 28 deaths of his ex-girlfriend, 27-year-old Amanda Thomas, and 25-year-old Carl Patrick Epley.

“I don’t know how this happens,” said Tina White-Masengill, Thomas’ sister. “My stepdad told police many times, ‘I don’t even think the guy’s a legal citizen.”‘

During his three years in Hannibal, Cazares managed to avoid detection, despite a few traffic violations and a property damage conviction after an arrest for allegedly beating up Thomas and tearing up her home. Thomas had a restraining order against Cazares, who got probation in the property-damage case.

Police say his name wasn’t in a database maintained by Immigration and Customs Enforcement. Police and Cazares’ boss also say he had authentic-looking identification, including a Social Security card. And police noted that Cazares speaks fluent English.

Hannibal police declined several interview requests from The Associated Press, but said soon after the killing that they had received several angry calls, some with racial overtones.

Days after the killings, rocks were thrown through plate-glass windows at the Mexican restaurant where Cazares worked. The FBI decided against opening a hate-crime investigation after concluding that it was vandalism, not retaliation.

Hundreds of messages related to the case were posted on the Hannibal Courier-Post Web site, with several questioning why authorities hadn’t been able to determine Cazares’ legal status before. One suggested police should conduct raids to seek out other illegal immigrants.

At a news conference, police Capt. James Hark told reporters that tracking illegal immigrants is a federal responsibility. He said the department is sympathetic to the victims’ families, “but, in retrospect, there’s nothing in the system that would have prevented this from happening.”