Mayor Alan Lambert's campaign manager also resigned Friday, The Detroit News reported.
All three said Lambert should have been the one to quit, and they did not think they could stay on under the circumstances.
"Hypothetically, if one of my police officers or firefighters showed the same lapses in judgments that you did and brought the same type of shame, mistrust, and embarrassment on the community, I assure you, that under my leadership they would not be working for us today," Police Chief Robert Dickerson said in his resignation letter. "In my mind, there cannot be a double standard just because you are the Mayor."
State troopers searched Lambert's home Thursday night. State officials say the raid is part of a corruption investigation that has been under way for three years.
Tim Keyes, the director of economic development, said in a letter of resignation he can "no longer in good conscience work for the current administration."
Robert McLachlan, the campaign manager, said he agrees with Dickerson. He said he will remain president of the Romulus Board of Education.
Romulus is a small industrial city west of Detroit and home to Detroit Metro Airport.