Four years after a case involving Milwaukee police Sgt. Jason Mucha changed the way Wisconsin courts consider claims of police misconduct, a federal gun case has fallen apart amid inconsistencies in testimony.

Police testimony is the lynchpin of almost every criminal case. If a defense attorney can successfully challenge an officer's truthfulness, charges aren't likely to stick. Prosecutors in the Milwaukee County district attorney's office are so leery of that possibility that they keep a list of troubled officers whom they won't call to the witness stand.

Yet despite being the focus of a 2006 appeal that opened the door for juries to hear about police officers' past wrongdoing, Mucha continues to supervise officers, avoid departmental discipline and testify in court.

The recent federal case against Daniel Pate shows how problematic an officer with a history like Mucha's can be for prosecutors. In an unusual move, the U.S. attorney's office asked that a firearms charge against Pate be dismissed "in the interest of justice" after Mucha and officer Michael Vagnini testified during a hearing this year.

James Santelle, U.S. attorney for the Eastern District of Wisconsin, said the evidence presented at the hearing was not what the prosecution had expected.

"Based upon the evidence at the hearing as it came out, we could not proceed with the case any further," he said in an interview. "Our assessment of the evidence now indicated it would be best to dismiss the case."

With Mucha's track record, the dismissal is no surprise, said Laurie Levenson, a professor at Loyola Law School in Los Angeles.

"For a federal prosecutor, one case is certainly not worth their reputation and credibility," she said. "They don't want the judge to say, 'I find this cop to be a liar, and I'm troubled that you put him on the stand.' "

The 2006 appeals court ruling came in the case of Walter Missouri. He was freed from prison after a three-judge panel said it was not in the interest of justice to take Mucha at his word. The justices ruled that several other men who had accused Mucha of misconduct should be allowed to testify on Missouri's behalf, taking a standard usually applied to defendants and applying it to police officers.

"It is not appropriate for this court, nor was it appropriate for the trial court, to assume that the defendant was lying and the officer was telling the truth," Judge Ted E. Wedemeyer wrote at the time.

Joined department in 1996

Mucha, who joined the department as a police aide in 1996, was promoted to sergeant in 2005. Through a police spokeswoman, he declined to be interviewed for this story.

A Journal Sentinel investigation published in 2007 detailed the Missouri case and revealed that at least nine other defendants in unrelated cases had accused Mucha of beating them, planting drugs or both, and that the police failed to investigate the pattern of incidents, which occurred over a three-year period. The accusers are mostly men with criminal records ranging from misdemeanors to serious felonies.

Some cases included Mucha and a partner. In others, a large number of officers were on the scene.

Felony charges against at least four of the defendants were either reduced or thrown out amid concerns about police conduct. That was the case with Missouri. He pleaded guilty to two misdemeanors, was given credit for the more than two years he already had served in prison and was released.

Missouri said he entered the pleas because he already had served the time and wanted to get on with his life.

Both the U.S. attorney's office and the FBI reviewed Mucha's actions for possible civil rights violations following the newspaper's investigation, but no charges were filed.

In court records and police use-of-force reports regarding the other cases, Mucha said the defendants had drugs or threw them to the ground as they fled. He contended that he used the minimum force necessary.

2009 encounter

Like many of the defendants in the earlier cases, Pate has a criminal record. It includes a misdemeanor battery and four felony drug convictions. He served prison time for a 2002 charge of possession with intent to deliver cocaine and remained on supervision when he encountered Mucha on Sept. 22 in the 2700 block of N. 16th St.

According to Pate's testimony at a March evidentiary hearing in federal court, he and his cousin were hanging out at a duplex Pate owns as an investment property. They got into the car and started pulling out of the driveway. Then Pate remembered he had forgotten his cigarettes and the car charger for his cell phone, so he pulled up the driveway again.

The next thing he knew, the police had kicked in the door of the house and wrestled him to the ground. Pate testified he heard police yell, "Stop!" but didn't think they were talking to him because he had done nothing wrong. He did not have a gun - just a cell phone - and had no idea why the police barged into the house and arrested him in the basement, Pate said.

Police said they found a gun in the basement, and Pate was charged with being a felon in possession of a firearm. He was first charged in state court, where the maximum sentence is two years. The case was later moved into the federal system, where the penalties can be much higher.

Illegal entry?

The evidentiary hearing was convened because Pate's attorney, Rodney Cubbie, contended that police had entered Pate's property illegally.

According to a transcript of the hearing, Mucha testified that he saw a man in a black hoodie run through an alley to Pate's house, where the man got into a car in the driveway. When the man got out of the car and approached the house, he pulled a gun from his waistband, Mucha said.

Mucha testified that he instructed Vagnini, an officer under his command, to kick in the door.

"I had no clue why this man was running into this house with a gun," Mucha testified. "I didn't know if he was going to be taking people hostage, if he was going to harm someone in there, if this was a set-up robbery where there was a car parked and they were going to rob and get away."

Mucha said he did not talk to the other person in the car and did not know who he was. However, under cross-examination, Cubbie asked Mucha to check his memo book. There, he had noted Pate's cousin's name, address, telephone number, birth date and driver's license number.

Also, when Pate was arrested that night, he was not wearing a black hoodie but rather a blue coat with a beige collar and no hood, according to testimony.

Finally, Mucha and Vagnini testified that Vagnini quickly found a gun in the basement, the only place he searched.

Cornell Williams, the tenant who lived on the first floor, contradicted that, saying police had searched his apartment and also had gone up the stairs to the second floor. The search took about 45 minutes, Williams said.

Assistant U.S. Attorney Stephen Ingraham, who prosecuted the case, filed the motion to dismiss the charge against Pate before U.S. District Judge Lynn Adelman ruled on whether or not the search was legal. The U.S. attorney's office for the Eastern District does not keep track of how often such motions are filed, but it is not common, Santelle said.

"If we feel that in good faith we do not have a basis to go forward, we not only have the option, we have the obligation to move to dismiss it in the interest of justice," he said.

Conduct clears probe

Pate lodged a battery complaint against Mucha and three other officers involved with his arrest: Vagnini, Paul Martinez and Jacob Knight. The three also did not want to be interviewed, Milwaukee police spokeswoman Anne E. Schwartz said.

Investigators from the Professional Performance Division ruled the complaint unfounded.

In doing so, they found that the officers were conducting a valid arrest and that Pate fled from police, according to a summary dated Nov. 3. Both of those conclusions later were called into question at the federal court hearing. The internal affairs investigators also noted that a criminal charge was filed against Pate. The investigative report into the officers' conduct was not updated once that charge was dismissed.

"It was not reopened (because) it was already investigated," Schwartz said.

Pate declined to be interviewed for this story.

Cubbie, Pate's attorney, said he was pleased the charge was dismissed.

"I'm grateful that the U.S. attorney's office took a fair look at it," Cubbie said. "That's all you ever ask for but you don't always get that."