BALTIMORE (AP) – A judge’s intense line of questioning Thursday appeared to expose weaknesses in the state’s case against an officer on trial for assault in the arrest of Freddie Gray, but legal experts cautioned against drawing any conclusions.

Baltimore Circuit Judge Barry Williams was bullish in interrogating prosecutors during closing arguments in the bench trial for Officer Edward Nero, repeatedly asking when the alleged assault occurred: Was it when Gray was first stopped or when he was handcuffed?

“I’m trying to figure out what you’re arguing,” the judge said.

“It’s a continuum,” Assistant State’s Attorney Jan Bledsoe said. “If you find putting him down in handcuffs wasn’t an assault, fine. But putting a cooperative citizen into a prone position, that’s an assault.”

Prosecutors say Nero, 30, unlawfully detained Gray and acted callously when he made a decision not to belt buckle Gray into a seatbelt when he was loaded into the back of a transport vehicle.

Gray died April 19, 2015, a week after his neck was broken in the van’s compartment while he was handcuffed and shackled, but unrestrained. Department policy calls for detainees to be buckled in.

Nero faces assault, misconduct in office and reckless endangerment charges. The assault charge, stemming from the allegation that Nero unlawfully touched Gray, carries a maximum of 10 years in prison and the other charges carry five-year maximums.

Nero did not testify. He waived his right to a jury, instead opting for a bench trial. The judge said he will deliver his verdict on Monday.

Nero’s attorney said he did what any reasonable officer would have done and that while being handcuffed is a “horrible thing” the law allows for it.

Prosecutors argued that Nero illegally arrested Gray after he ran from another officer in the Sandtown-Winchester neighborhood. That officer, Lt. Brian Rice, called for backup and Nero and another officer responded.

Bledsoe, the prosecutor, told the judge that because Nero didn’t ask his supervisor or figure out whether there was probable cause to arrest Gray, he failed in his duty. Additionally, prosecutors argued that the officers arrested Gray before determining whether or not he was armed, dangerous and posed a threat – a necessary pre-arrest step that must be taken under rules governing temporary detentions, also known as Terry stops.

Once Gray was in handcuffs, officers found a knife on him, but the judge previously ruled that the knife’s legality wouldn’t be part of the trial. In a police report, Officer Garrett Miller cited the knife as the reason for Gray’s arrest.

Williams also peppered Bledsoe with questions about whether any police officer who arrests a suspect without probable cause should face criminal prosecution.

“You’re saying that’s a criminal assault, as opposed to just suppressing what’s found in that search?” the judge said.

The prosecutor replied, “yes, it’s a criminal assault.”

Later, during rebuttal remarks, Chief Deputy State’s Attorney Michael Schatzow sought to clarify Bledsoe’s argument.

“If the officer makes an arrest without probable cause and his actions are objectionably reasonable, that’s not a crime,” he said, adding that Nero’s actions were unreasonable.

“Everything they did was at the margin, the extreme and without justification,” Schatzow said. “The initial stop was OK. The initial handcuffing was not.”

The defense answered a handful of questions from the judge, but did not get near the grilling prosecutors faced.

The judge “appeared to be troubled by the state’s position that any arrest where it’s ultimately determined that probable cause did not exist amounts to a crime,” said attorney Warren Alperstein, who was in the courtroom but is not involved in the case. “And it was so significant that the state in rebuttal had to clarify their earlier statement.”

But David Jaros, an associate professor of law at the University of Baltimore, said it’s risky to extrapolate too much from a judge’s questioning.

“He’s certainly identified some of the significant challenges that are endemic in the prosecution’s theory in the case,” Jaros said. “But the fact that he didn’t grill Mr. Zayon isn’t any suggestion that he’s bought Zayon’s theory of the case either. But Ms. Bledsoe’s claim that an arrest without probable cause would be a crime, and at the end of the day I think she was really saying an unjustified arrest, that’s pushing the envelope of what we’ve typically thought of as criminal activity.”

Nero is the second of six officers to stand trial. Officer William Porter’s manslaughter trial ended with a hung jury.