Throughout his career, Berrios combined government sector jobs, elected office, unpaid political party leadership positions, and private-sector proprietorships in lobbying, consulting and insurance sales.

In the press and in the courts, Berrios has repeatedly defended his right as an elected official to hire relatives and to accept campaign contributions from those with business with his office.

At age 13, Berrios got a job as a dishwasher in the Tower Club, a private restaurant on the 39th floor of the Civic Opera House,[2] worked there for seven years, and eventually become a waiter.

[6] In October 1974, Keane was convicted of conspiracy and mail fraud for using his elected office to profit from illegal real estate deals.

[8] Nedza's political protegés included Alderman Miguel Santiago of the 31st ward, the only Hispanic on the Chicago City Council at the time, and Berrios.

[9] Chicago-area Latino groups contested the legislative district map of the Illinois General Assembly in United States federal court.

In 1982, Nedza sponsored Berrios, at the time chief clerk to Cook County Board of Appeals commissioner Harry H. Semrow, in the 9th district.

[15][16] Berrios maintained his job in Chicago as chief clerk of the Cook County Board of (Tax) Appeals while serving part-time as a legislator in the state capital in downstate Springfield, Illinois.

[18] In March 1987 then former State Senator Edward Nedza, Berrios' mentor, was indicted in a federal investigation of bribes allegedly paid to city licensing officials.

[19][20] Berrios allied with Alderman Edward Vrdolyak, during Chicago Mayor Harold Washington's first term, the Council Wars era.

In 1987 Raymond Figueroa, with Washington's backing, defeated Berrios's candidate for alderman, Miguel Santiago, which helped close the Council Wars.

[26] In accordance with state law, the Chief Judge of the Cook County Circuit Court appointed a temporary replacement, attorney Thomas A. Jaconetty, 34, a deputy assessor with the Board of Appeals since 1981.

[30] In the Democratic primary, Berrios won the nomination with a sizable margin over Jeffrey Paul Smith, an assistant corporation counsel with the City of Chicago whose candidacy was sponsored by Quinn, by then a former Commissioner.

In October 1990, Berrios added a part-time job as a legislative aide to a political ally, Democratic State Representative Miguel Santiago.

[33] From 1988 to 1993, Panayotovich and Berrios won a $185,000 no-bid contract as the Illinois Department of Transportation's (IDOT's) liaison with lawmakers and municipal officials.

[34][35] On March 11, 1994, FBI agents executed a search warrant to confiscate records from the Cook County Board of (Tax) Appeals as part of an ongoing investigation.

[36] Weeks later, federal agents investigating ghost payrolling subpoenaed financial records regarding several past and current employees of the Board, including Berrios and Panayotovich.

[43] In a 2013 federal bribery trial of a Board of Review analyst, in secret recordings by an undercover FBI informant from 2008, the defendant named Berrios as a recipient of bribes.

[44][45][46] While Commissioner on the Board of Review, Berrios' sister, sister-in-law, son and daughter worked for the county at annual salaries ranging from $48,000 to $86,000.

[48] Berrios also hired, as a deputy chief commissioner, election law attorney Jaconetty, who wrote the chapter on ballot access in the courseware of the Illinois Institute for Continuing Legal Education.

[4][56][57][58] "Illinois, thy name is conflict of interest," wrote Better Government Association Executive Director Andy Shaw in the Chicago Tribune in 2009.

[74][75] The Board of Ethics sent letters to 15 tax attorneys, warning that their donations to Berrios during the 2010 election cycle had exceeded the county campaign contribution limits.

[80][81] Days after taking office, Berrios hired his son, sister and Jaconetty to work for him, bringing them over from the property tax appeals board.

[89] The federal-court appointed attorneys monitoring City of Chicago and Cook County compliance with the Shakman decrees, designed to prevent politics from influencing most personnel decisions, raised objections to as many as 27 hirings and firings in the first month of the Berrios administration of the Assessor's office.

[92] On July 17, 2013, the Cook County Board approved $529,000 in settlements to 11 former employees of the Assessor's office that the court-appointed Shakman decree monitor had determined had been fired unlawfully by Berrios for political reasons.

[105] Cook County State's Attorney Anita Alvarez declined to represent Berrios or the Board of Ethics in the nepotism issue, citing conflict of interest.

[109] The Board of Ethics petitioned the courts for a special prosecutor, and a judge appointed attorney and former Chicago Inspector General David H. Hoffman.

[118] Berrios is a partner with Sam Panayotovich in, and secretary of, a lobbying firm, B-P Consulting, Inc. with offices in Springfield and downtown Chicago.