A source in county government, who spoke to the sheriff, told Eyewitness News that Baca intends to announce his resignation Tuesday morning.
Baca, 71, called the Los Angeles County Board of Supervisors and met individually with members of his command staff to make his intentions known.
The decision comes in the middle of Baca's re-election campaign, and as 18 of his deputies face federal charges for inmate beatings.
Baca, who is serving his fourth term, has been facing criticism following an FBI investigation into corruption and abuse at the county's jails.
The federal investigation described a culture of violence at Men's Central Jail and Twin Towers Correctional Facility. It alleged that deputies would go out of their way to use excessive force.
Baca has insisted that the allegations do not reflect on the department as a whole.
The sheriff has also come under fire for questionable hiring practices, including hiring a pastor with ties to medical marijuana to an advisory position with the department at a six-figure salary. An Eyewitness News investigation uncovered that in November.
Baca has acknowledged other questionable hiring practices, including friends and relatives of top officials getting an inside track for jobs within the department, and also the hiring of dozens of deputies who were fired from other departments.
Some members of the department say they have been retaliated against for supporting Baca's opponents in the upcoming election.
Baca and his department have also faced several lawsuits from the ACLU on behalf of former jail inmates.
Just on Monday, Baca announced his support for the creation of a citizen's review board that would oversee the sheriff's department.