Baca said the admission prompted him to create a 35-person task force of seasoned investigators and other experts to examine a growing number of allegations of deputy misconduct in the jails.
The FBI is investigating allegations of deputy abuse and other misconduct. In a recent undercover sting, federal agents targeted Michel, offering him $1,500 to sneak a cellphone to an inmate who he was unaware was an FBI informant.
Baca's letter, which was sent Friday to Supervisor Michael D. Antonovich and obtained by The Times, said sheriff's investigators interviewed Michel after deputies at Men's Central Jail found the cellphone among the inmate's belongings on Aug. 8. The deputy admitted smuggling the phone as well as cigarettes and a lighter to the inmate but denied taking other contraband into the jail, the letter said.
Michel, 38, also "made statements which implicated him, along with several other jail employees, as having participated in four prior unreported incidents of improper uses of force," according to the letter. Michel, who could not be reached for comment, has since resigned from the department.
Lt. Steve Leavins of the department's Internal Criminal Investigations Bureau declined to detail how many deputies Michel had implicated, saying he did not "want to tip our hand." He said that the force used may have been excessive and unreported but that it is unclear whether any inmate was injured.
"If Michel is being truthful and we can substantiate his claims, there's a likelihood it was criminal in nature," Leavins said.
Asked why Michel would tell investigators about wrongdoing he was involved in, Leavins said: "I'll characterize it this way, he's an unusual guy."
In an interview with The Times on Saturday, Baca said Michel's conduct demonstrated that some jail guards were violating the department's rules by not reporting whenever they use force on an inmate.
"We think our standards and policies are very high," Baca said. "The point of my memo shows we have a problem and Michel is an example of the problem."
In his letter, Baca said claims of jailhouse abuse are difficult to prove because inmates believe they will suffer retaliation from other inmates for cooperating with law enforcement. He said he plans to turn over the results of the task force's probe to the U.S. attorney's office for possible further investigation by the FBI.
The letter's details provide more evidence that the FBI's inquiries have helped uncover allegations of deputy misconduct. Baca, who was initially critical of the FBI's tactics in the probe, said Friday that he would welcome a so-called pattern and practice investigation into whether the department is violating the civil rights of inmates. His comments came as county Supervisors Gloria Molina and Zev Yaroslavsky called for an independent review of the jails.
Civil rights lawyer Connie Rice praised the sheriff for his apparent reversal, saying any investigation needed to go beyond counting allegations of deputy-on-inmate force and focus on the underlying reasons for violence in the jails.
She noted that department rookies begin their careers in the jails. Spending years in the detention facilities can "give rise to a cynical and overly paranoid mind-set" among deputies, she said.
"I'm hoping that the feds won't do a drive-by investigation," Rice said. "There needs to be a carefully planned, systematic excavation of the sheriff's culture."
Rice was among more than two dozen lawyers, inmate rights advocates and others who sent a letter last month to U.S. Atty. Gen. Eric H. Holder Jr. seeking a federal pattern and practice investigation. The Justice Department in August announced that it had launched such an investigation into allegations of racial discrimination by deputies in the Antelope Valley.
Rice said such a jail probe should involve interviews with deputies, inmates and people outside the department who understand the jail's problems, such as civil rights attorneys who have sued the county and advocates for the welfare of inmates.
A pattern and practice investigation could have dramatic consequences for Baca's department. Such probes often take years to complete, and their results can lead to demands for comprehensive, costly fixes.
In August, for example, the Justice Department's Civil Rights Division concluded a three-year investigation into the Miami-Dade County jail system, the eighth-largest in the nation. The probe involved interviews with corrections staff, medical and mental health providers, prisoners and community members.
The department found that guards engaged in a pattern or practice of excessive force against inmates, including abusive and retaliatory conduct, and were indifferent to the suicide risks and mental health needs of prisoners. The probe also found a failure to provide adequate health treatment.
In a letter to the Miami-Dade County mayor, the head of the department's Civil Rights Division demanded that the county immediately implement nearly 100 detailed remedies, such as increasing video surveillance in the jails and improving training for guards. Assistant Atty. Gen. Thomas E. Perez wrote that the Justice Department would prefer to work with the county to resolve its problems but could file a lawsuit to force compliance.
That's a scenario the Los Angeles County Probation Department could also face. The county has for years failed to comply with Justice Department demands to improve health and safety for offenders in juvenile detention.
In 2001, the city of Los Angeles agreed to enter into a consent decree that resulted in the LAPD operating under federal oversight for eight years after the Rampart corruption scandal. The decree required the department to undertake dozens of wide-ranging reforms meant to tighten internal checks on officers' conduct and subjected the department to rigorous audits by a monitor who reported to a federal judge.
Document: Read the full letter