The D.C. police department fired 55 officers in the past fiscal year, nearly triple the number recorded two years ago, according to newly released statistics.

More officers were dismissed in fiscal 2005, which ended Sept. 30, than in the previous two years combined. Thirty-two officers were fired in fiscal 2004 and 19 in fiscal 2003.

Police and union officials said the increase does not suggest a rise in improper behavior. But they differed on what is fueling the trend.

Police officials said the number of firings spiked because of a new D.C. law requiring that internal affairs investigations be completed within 90 days. The law, which took effect in September 2004, forced officials to finish work on a backlog of old cases while keeping up with new matters coming into the disciplinary system.

"Investigations are being handled more expeditiously," said Assistant Chief Shannon Cockett, who oversees the department's office of human services.

Union officials said that the department is acting more aggressively against officers and that some have been unfairly fired.

D.C. police declined to identify the fired officers, citing personnel rules, but provided a statistical breakdown of firing data to The Washington Post under the Freedom of Information Act.

The surge in dismissals was particularly sharp for officers who had been on the force for more than 18 months: Forty-two such officers were fired last fiscal year, up from 17 in 2004 and seven in 2003.

The number of fired officers who had been on the force for fewer than 18 months -- probationary employees who do not have the same administrative rights as veterans -- remained steady.

Of those fired in the past fiscal year, the cause for 18 officers was unbecoming conduct, a broad category that includes being charged with a crime and harassment. The cause was neglect of duty for two others and "truthfulness/falsification of records" for four officers, data show.

Nine officers were fired after they were convicted of criminal charges. In 2003 and in early 2004, the department recorded a spike in the number of officers arrested on criminal charges.

Police officials said they were unable to provide statistics on the number of more recent officer arrests because of computer system problems that they are trying to correct.

Because the department would not release the names of fired officers, The Post was unable to cross-check names against criminal records to determine whether a jump in the number of arrested officers contributed to the increase in firings.

The largest group of officers fired last fiscal year joined the force in 1989 or 1990, a period when a massive hiring push imposed by Congress led police officials to cut corners on recruiting, background checks, psychological testing and training.

Last fiscal year, 15 officers from those two classes were fired, up from eight in 2004 and one in 2003.

"There is a strong correlation to folks hired in those years" and the increase in firings, Cockett said.

Cockett and Police Chief Charles H. Ramsey said they had noticed no other trends in the data. They denied the union's claims that police officials were being more aggressive in their discipline.

"I don't have any control when these cases come before me," Ramsey said. "There is no particular trend or pattern. It's just kind of all over the place."

Union officials maintained that the latest statistics indicate that police officials are handing out stiffer punishments. Cockett and Ramsey routinely go against recommendations for lesser disciplinary action made by internal review panels of supervisors, the union leaders said.

All officers who face firing are granted hearings before such panels, which weigh evidence and recommend punishment. Cockett and Ramsey can overrule the panels and impose stiffer or lighter sanctions.

"We are tired of seeing people getting fired for things that two or three years ago they weren't getting fired for," said Sgt. Gregory I. Greene, chairman of the D.C. police labor committee for the Fraternal Order of Police Lodge 1.

Union attorneys estimated that the internal panels had recommended punishment short of termination for about 15 officers who were then fired last fiscal year.

"Why bother going through with the process if they are just going to overrule it?" asked Harold Vaught, a union attorney.

Vaught pointed to the case of a 44-year-old officer who was fired last November as an example. The officer, who joined the force in 1990 and whose name was withheld by union officials, admitted arguing with other officers at the station house during an altercation in 2003. A panel recommended a 10-day suspension, but Cockett and Ramsey fired the officer.

D.C. Council member Phil Mendelson (D-At Large), chairman of the judiciary committee, said he plans to review the latest statistics but isn't sure what to make of them.

"We're looking at the numbers," Mendelson said. "I wouldn't say it's a bad thing. I wouldn't say it's a good thing."