Two state lawmakers have called for the resignation of Maricopa County Sheriff Joe Arpaio because his office mishandled hundreds of sex-crimes investigations in the mid-2000s.

Arpaio, in turn, called a news conference Wednesday to highlight his immigration-enforcement measures but ended by promising to hire an outside expert to evaluate the Sheriff's Office's handling of sex-crime cases.

State Reps. Ruben Gallego and Katie Hobbs, both Phoenix Democrats, had a news conference at the Capitol on Wednesday morning to ask for Arpaio's resignation, two days after U.S. Rep.Ra�l Grijalva, D-Ariz, also said Arpaio should resign.

"We need to reinforce when someone in the United States reports any kind of sexual abuse to law enforcement, we will investigate it," Gallego said. "This is not a Third World country, and Sheriff Joe should not be acting like he's running one. When there is a problem, law enforcement needs to recognize that there's a problem and deal with it."

Hobbs said the calls for resignation were not a partisan issue and that voters would have a chance to express themselves in the November election if Arpaio did not step down.

Arpaio, with his immigration-enforcement news conference hijacked by questions about the sex-crimes cases, said the legislators calling for his resignation were no different than other politicians who have publicly attacked him through the years.

"The bottom line is, we're going to let the voters decide next year who they want their sheriff to be. I'm not going to let elected officials with their own agenda that have a 'D' next to their name try to get some media attention using my name to get me to resign," he said. "That's my answer to the elected officials, the handful, trying to intimidate me."

The calls for Arpaio's resignation have come in recent days after national media outlets began reporting this week about hundreds of sex-crimes cases the Sheriff's Office mishandled from 2005 to 2007.

Valley media outlets reported last spring that the Sheriff's Office failed to adequately investigate more than 400 sex-crimes cases, including dozens in El Mirage, over two years because of poor oversight and former Chief Deputy David Hendershott's desire to protect a key investigator from bad publicity.

The problems with the cases and Hendershott's motivation to protect an investigator were detailed in a lengthy report released in May. The report was the result of a months-long internal investigation Pinal County Sheriff Paul Babeu conducted that resulted in the dismissal of Hendershott and two other administrators in Arpaio's office.

A story picked up by national media outlets over the weekend reignited a furor over the botched cases.

According to the Sheriff's Office, detectives reactivated 432 sex-crimes cases from throughout the Valley after concerns about the cases were raised, making 19 arrests. Of the remainder, 115 were determined to be unfounded, 67 were classified as "cold cases" and 221 were "exceptionally" cleared without arrest.

Ten cases remain viable, authorities say.

"We took care of the problem many years ago," Arpaio said.

An internal investigation into the mishandled cases is complete and sheriff's administrators are in the process of disciplining the deputies involved, the sheriff added.

That internal report will be released after the disciplined employees have exhausted the appeals process, a sheriff's spokesman said.

Instead of resigning, Arpaio said, he plans to launch a nationwide search and hire an outside expert to assess how the Sheriff's Office handles sex-crime investigations. He also offered the undetermined expert to other law-enforcement agencies in the Valley who have dealt with their own botched sex-crimes cases.

"I don't care what it costs to get the expert here," Arpaio said. "It's my top priority."

The elected officials who called for Arpaio's resignation Wednesday said the sheriff's priorities, whether they were targeting elected officials or undocumented immigrants, contributed to a culture in the Sheriff's Office that allowed sex-crime investigators to neglect the cases.

Arpaio, whose news conference was designed to highlight the arrest of two undocumented immigrants this week, each of whom had previously been deported at least 13 times, said critics would not deter his office's immigration-enforcement efforts.