ALBANY — State Inspector General Kristine Hamann, who was appointed by Governor Spitzer and was criticized for her two investigations into his administration, has resigned.

Her spokesman, Stephen Del-Giacco, said Ms. Hamann submitted her resignation yesterday and it will be effective April 10. Her one-page letter said she was honored to serve and proud of her accomplishments in just over a year in office.

But Ms. Hamann’s biggest investigations drew severe criticism by the Senate’s Republican majority that was in open conflict with the Democratic Mr. Spitzer and his administration.

Republicans faulted her for her investigation of Mr. Spitzer when his top aides were accused of plotting to discredit the Senate majority leader, Joseph Bruno. Her July 2007 report on the scandal involving the use of state police to compile travel records on Mr. Bruno was a one-page letter that said she concurred with Attorney General Cuomo, who found no laws were broken but that aides had acted inappropriately.

She said she determined in her investigation that she had a conflict of interest because her boss, the then-secretary to the governor, Rich Baum, was one of the Spitzer officials who had internal conversations about the case. Mr. Baum recently left the executive chamber.

In February, Ms. Hamann also faced scrutiny for her 10-month investigation of a former energy policy adviser to Mr. Spitzer who was accused of threatening the job of a Republican-appointee on the independent Public Service Commission.

Her investigation found no conclusive proof that Mr. Spitzer’s energy adviser, Steven Mitnick, threatened the job of a member of the state Public Service Commission, Cheryl Buley, or tried to force her to vote for Mr. Spitzer’s policies. Ms. Buley had said Mr. Mitnick threatened her job last year to make room for an appointment by Mr. Spitzer.

The Inspector General’s office is responsible for detecting and investigating allegations of corruption, fraud, criminal activity, conflicts of interest, and abuse involving state agencies, departments, commissions, and authorities headed by appointees of the governor.

Governor Paterson is expected to replace Ms. Hamann in the $145,000-a-year job.

The governor accepted the resignation and thanked Ms. Hamann for her service, the governor’s spokesman, Errol Cockfield, said. The special deputy to the inspector general, Dennis Martin, was named acting inspector general.