A Bay Shore man convicted last month of sexually abusing a girl for four years was sentenced Thursday to a maximum 25 years in prison, Suffolk prosecutors said.

Robert Kattau, 43, was also sentenced to 20 years of post-release supervision.

A jury on Feb. 10 convicted Kattau of first-degree sexual conduct against a child, a violent felony, and endangering the welfare of a child, a misdemeanor, officials said.

“Unfortunately, we are not pleased with the court’s sentencing him to the maximum,” David Geller, Kattau’s Legal Aid attorney, said in a statement.

Geller said he is appealing Kattau’s conviction, a process expected to take months. The defense attorney argues there was not enough evidence to convict his client, who he said was “tricked” into signing a confession.

Prosecutors said Kattau started sexually abusing the girl when she was 8 in summer 2012 and didn’t stop until he was arrested last March. The victim told a friend, whose family told school officials.

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Robert Clifford, spokesman for the Suffolk district attorney’s office, has said Kattau blamed the girl for his conduct.

But at sentencing, Kattau did not defend himself, the spokesman said.

“They asked him if he wanted to say anything,” Clifford said, “and he said one word: ‘Nope.’ ”

In a statement, District Attorney Thomas Spota described Kattau as “a sexual predator who has shown no remorse for his crimes against this young victim, a girl who exhibited tremendous courage in coming forward to see him tried, convicted and now sentenced to the maximum prison term the law allows.”