SAN BERNARDINO • Former Assistant Assessor Adam Aleman pleaded no contest to four felony counts Tuesday and agreed to testify against former coworkers in the Assessor’s Office under Bill Postmus.

Aleman’s felony convictions — all related to altering public records sought by the grand jury — will be reduced to misdemeanor convictions if he “testifies truthfully and fully cooperates with law enforcement” in the public integrity probe into the Assessor’s office, said Susan Mickey, spokeswoman for the San Bernardino County District Attorney’s office.

Aleman, 26, pleaded no contest to two felony counts of tampering with a public document, one felony count of filing fraudulent claims and one felony count of vandalism.

Those charges are part of an amended complaint filed by the county District Attorney’s office.

In San Bernardino County Superior Court, Aleman promised Judge John Martin he would testify against former Assessor’s office colleagues, including former Assistant Assessor Jim Erwin and former Intergovernmental Relations Officer Rex Gutierrez, who is also a Rancho Cucamonga City Councilman, and others.

Last month District Attorney’s office investigators arrested Gutierrez on two felony charges of grand theft and misappropriation of public funds. In March investigators arrested Erwin on 10 felony charges for failing to disclose more than $14,000 of gifts from a developer who sued the county for $300 million.

Erwin and Gutierrez are also among six former Assessor’s office workers named defendants in the county’s civil suit alleging Postmus and his executive staff committed timecard fraud, abused county resources and used the office as a personal political machine.

Aleman, who did not return a call for comment, is scheduled to appear in court for sentencing Jan. 7.