From the outside, the Miami Police Department seems perpetually torn by scandal, with the latest rip in the fabric — Wednesday’s arrest of a veteran officer accused of extortion — coming only days after a narcotics sergeant was convicted of corruption in an embarrassing federal trial that pitted a group of veteran detectives against their own boss.

But police and city officials say the latest string of arrests and investigations — playing out against the backdrop of an ongoing Justice Department probe into seven fatal police shootings — obscures the recent efforts of Police Chief Manuel Orosa to purge the department of bad cops.

“We cannot be following around every cop 24-7,” said Orosa, who formally took over as chief 13 months ago. “We are doing everything we can to ensure our officers are doing the right thing.”

That includes adding five more detectives to the department’s Internal Affairs Unit, which has been working hand-in-glove with the FBI in its current investigation of up to 10 officers suspected of providing protection to a Liberty City gambling ring and other crimes.

The first of those officers, 41-year-old Nathaniel Dauphin, was arrested Wednesday on an extortion charge for allegedly helping organize an off-the-books protection squad for an illegal sports-betting racket run out of the Player’s Choice Barber Shop in Liberty City.

Internal Affairs detectives also worked with the FBI in the 2010 investigation of Sgt. Raul Iglesias, a narcotics detective who was convicted Jan. 18 of eight felonies, including obstruction of justice and taking drugs and money from suspects. A second detective, Roberto Asanza, pleaded guilty to misdemeanor drug charges stemming from the same investigation, and later testified against Iglesias — as did four detectives who worked on his team.

The FBI’s role

Miami’s Internal Affairs officers first began working in 2009 with the FBI-led Miami Area Corruption Task Force, a team that also includes officers from Hialeah and Miami Beach, and agents from the U.S. Customs and Border Protection-Office of Internal Affairs. The task force, which was launched when Orosa’s predecessor, Miguel Exposito, was chief, focuses on both police and government corruption. It is the FBI’s largest anti-corruption squad in the country, said John Jimenez, the supervisory special agent overseeing it.

Of the nine Miami police officers arrested since 2010, seven have been busted by the FBI’s team.

Jimenez noted that participation in the team can be politically risky for the police departments, because the task force could end up unearthing embarrassing information. “We’re really proud of the fact that police departments are willing to participate,” he said.

Since taking over as chief, Orosa has increased the number of officers on the FBI task force from three to nine.

Orosa said he does not believe the string of arrests points to a systemic problem with his department, and emphasized that the arrested officers make up just a fraction of the department’s 1,100-member force.

“There’s always a small percentage of people who are corrupt,” Orosa said. “It’s unacceptable, and that’s why we are trying to root out the bad apples.”