Garcia, 40, was being held in Illinois on suspicion of four counts of first-degree murder and four counts of using a weapon to commit a felony, Schmaderer said. An Illinois State Police official declined to discuss details of Garcia's arrest or detention, and said any questions should go to Omaha police.
Garcia didn't have a listed phone number in Terre Haute or in Chicago, where he previously lived, and it wasn't immediately clear if he had an attorney. No one answered the phone at his family's home in Walnut, Calif., Monday evening.
Public records show that since 2003, Garcia has held medical licenses in California, Illinois and Indiana, but his temporary Indiana license expired in January.
Investigators believe that in May, Garcia broke into the Omaha home of Creighton University medical school pathology professor Roger Brumback and fatally shot him and stabbed his wife Mary to death, Schmaderer said. They also believe Garcia was behind a 2008 home invasion in which the 11-year-old son and family housekeeper of another pathology department professor, William Hunter, were stabbed to death.
In 2001, Roger Brumback and Hunter fired Garcia, who was a department resident, because he had displayed erratic behavior, Schmaderer said. The police chief didn't provide further details of the alleged behavior and he declined to discuss the evidence used to build the case against Garcia.
A task force of local, state and FBI investigators has been working on the case, and its members believe Garcia fits all the criteria of a serial killer, Schmaderer said.
"We didn't feel this individual would stop unless an arrest was made," he said.
Schmaderer said investigators believe Garcia acted alone, and that they are also searching several places where Garcia has lived since 2001.
The Omaha attacks happened in neighborhoods where homicides are rare. The city averages about 40 per year.
One of the Brumbacks' three children, Darryl, said the family had no comment about the arrest. A male relative of Sherman's also declined to speak. The Hunter family didn't respond to a phone message seeking comment.
Hunter's son, Thomas Hunter, and housekeeper, Shirlee Sherman, were killed at the family's 3,700-square-foot home in the historic neighborhood of Dundee, which is home to some of the city's most prominent residents, including billionaire investor Warren Buffet. The case was featured last year on an episode of "America's Most Wanted," and a $54,000 reward was offered.
Schmaderer said Monday that investigators don't believe the boy and the housekeeper were the intended targets of the attack.
Authorities have released few details about the attack on the Brumbacks, other than manner in which they were killed. Their bodies were discovered in their west Omaha home on May 14.
The task force was set up after the Brumbacks' deaths to investigate whether they were tied to the unsolved 2008 killings. Schmaderer declined to say what led investigators to Garcia.