After seven days of testimony alleging that an elite Philadelphia narcotics unit routinely cracked skulls, pocketed drug money, and lied on police reports to cover up its crimes, the federal jury hearing the corruption case against six of its members could be excused for wanting answers to a few nagging questions.

Among them: Where were these officers' bosses? And what did they have to say when the FBI showed up on their doorsteps?

The answers, as FBI case agent John Hess testified Thursday, are complicated.

Police Commissioner Charles H. Ramsey supported the investigation from the beginning, he said.

But agents did not try to contact the drug unit's direct supervisors until earlier this year, well after the six were indicted. And they never reached out to others, including one who participated in some of the drug raids now part of the government's case.

Defense lawyers have pointed to those decisions as signs of a flawed FBI probe. The say agents cut several corners, suggesting they approached their investigation of Officers Thomas Liciardello, Brian Reynolds, Michael Spicer, Perry Betts, Linwood Norman, and John Speiser already convinced of their guilt.

"They didn't want the truth," Reynolds' lawyer, Jack McMahon, has said. "They wanted to knee-jerk accept what some drug dealer said without corroborating it with anyone who might say something different."

Lawyers for the indicted officers plan to call several supervisors, including Ramsey, as witnesses.

Hess, the FBI case agent, and federal prosecutors defended the probe.

"Until the indictment, did you know how high the corruption went?" Assistant U.S. Attorney Anthony Wzorek asked Hess. "Did you know how far and wide it went? You didn't know who was involved."

Hess replied: "I still don't know for certain."

Even if he were certain the supervisors had no involvement in the drug unit's alleged crimes, Wzorek asked, "did you expect to get cooperation from Philadelphia police officers against their brother officers?"

Prosecutors have alleged that Liciardello and his codefendants shook down drug suspects for years with gang-like efficiency, often using excessive force and deception to steal drugs and money that they failed to report on police property receipts.

Throughout the testimony of government witnesses, the names of four narcotics unit supervisors have surfaced again and again: then-Chief Inspector William Blackburn, Capt. Chris Werner, Sgt. Joe McCloskey, and Lt. Robert Otto.

FBI agents tried to interview Blackburn and Werner this year.

Hess testified that they said they would talk to investigators only if granted immunity and a guarantee that their statements would not be used as a basis for Internal Affairs action. Prosecutors refused to agree to those terms, and interviews with the men never happened.

McCloskey, the unit's direct supervisor, signed several police reports and property receipts that prosecutors now allege were falsified to cover up theft.

Hess made clear Thursday that his investigation did not turn up evidence implicating McCloskey in any of the crimes alleged against Liciardello and his codefendants.

Prosecution witnesses, however, have suggested that McCloskey may not have been at the scenes of many of the reports that he signed. For instance, he signed a property receipt for $8,500 seized during an April 2012 bust that, unbeknownst to the drug squad, the FBI staged in hope of catching Liciardello and others committing a crime.

Though McCloskey's name appeared on the paperwork for that bust, hidden-camera video of the operation shows no sign he was present.

McCloskey agreed to be interviewed when approached by FBI agents in January, but demanded that the session be videotaped and that prosecutors not use his statements against him in court.

"It's unusual for us to do that," Hess said, "but we agreed to it."

Most puzzling to defense lawyers, however, was the FBI's failure to try to contact Otto, who was once McCloskey's boss. He has since been elevated by Ramsey to oversee other investigative units.

Otto was also present, according to government witnesses, at several of the drug busts in which officers are alleged to have stolen drug cash. According to one police report, Otto made one of the cash seizures federal prosecutors have since characterized as suspicious.

Hess said Thursday he did not believe the narcotics unit members conducted any illegal activity in front of Otto. Still, when asked why the FBI never sought to speak to the lieutenant, Hess was forthright.

"If he were going to tell me the truth, I would have," the agent said. "I didn't think he was going to tell me the truth."

Reached by phone Thursday, Otto declined to comment. Efforts to reach McCloskey, Werner, and Blackburn were unsuccessful.

The trial is set to resume Friday.

215-854-2608 @jeremyrroebuck

Inquirer staff writer Aubrey Whelan contributed to this article.