According to city officials, Morrison resigned to pursue "other interests."
This resignation comes during a continuing investigation suggesting Morrison may have violated state laws. Morrison's lawyer, Charles Kincade, says she is pursuing another opportunity offered to her in the engineering field.
"It's not related to the criminal investigations, it's unrelated to that," he said. "She was presented with other opportunities at this time, she intended to pursue those and that's what she's doing."
An investigation into possible payroll fraud in the engineering department comes from an audit last year, suggesting Morrison may have violated state laws when she hired an employee and paid him for work he may not have actually done.
Kincade says the case and her resignation are separate situations.
"She didn't resign because of the investigation and I don't believe her resignation will have any impact whatsoever on the investigation."
That investigation is still in the hands of the District Attorney's office.
"Witnesses are still being interviewed and the case is still being reviewed, and we hope to take it to the grand jury in the next 30 days," said Cindy Lavespere with the DA's office.
Lavespere says over the past year, a lot of work has gone into this case.
"I just know that it is a work in progress at the moment. It involved a lot of information," she said.
Mayor Jamie Mayo says the resignation came as a surprise.
"Of course, I accepted her resignation and I wish her well," he said.
Professional engineer Richard Paulus --- a 5-year city employee with 52 years of experience in the engineering field -- will serve as acting city engineer for now.
"We'll do everything that we can to get the right person in place, to continue moving projects forward," Mayo said.
Mayo says no time has been set yet on naming a new city engineer.