Donald Trump's campaign manager won't be prosecuted for battery after briefly grabbing a female reporter's arm at a campaign event, but prosecutors said Thursday the situation might have been avoided with two simple words: I'm sorry.

State Attorney Dave Aronberg said at a news conference there wasn't enough evidence to justify bringing misdemeanor simple battery charges against Corey Lewandowski for the March 8 dustup with Michelle Fields, then a reporter for the conservative Breitbart News website.

Although Lewandowski's act wasn't criminal, Aronberg said there may have been an easy way to defuse things.

"In a case like this we do encourage an apology. Had an apology been given at the beginning of all this, we could have avoided the whole criminal justice process," Aronberg said.

Although police in Jupiter, Florida, found enough probable cause to charge Lewandowski last month after viewing a video recording of the encounter, Aronberg said prosecutors are held to a higher legal standard.

"We have the burden of proving each case beyond a reasonable doubt," he said.

In a Thursday night appearance on "Hannity" on Fox News, Lewandowski thanked Trump for supporting him and said the decision to drop the charges was a relief.

"This has really taken over a big piece of my life, and I'm glad it's behind us," he said.

Lewandowski denied grabbing Fields and Republican front-runner Trump stood by him, rejecting calls by his opponents to fire or discipline him. Instead, he went after Fields, accusing her of exaggerating and changing her story.

Not backing down, Fields tweeted a photograph of her bruised forearm and said she had been yanked backward.

The investigation proved that Lewandowski "pulled Ms. Fields back" as she attempted to interview Trump, according to a memo by another prosecutor, Chief Assistant State Attorney Adrienne Ellis. The memo says Lewandowski could have believed Fields was "making unwanted physical contact with Mr. Trump" that led him to pull her away.

"Mr. Lewandowski may have had apparent authority to assist in the protection of the candidate, specifically to maintain the 'protective bubble' around the candidate," Ellis wrote. "While the facts support the allegation that Mr. Lewandowski did grab Ms. Fields' arm against her will, Mr. Lewandowski has a reasonable hypothesis of innocence."

Ellis added that the video showed Trump moving his arm away from Fields' initial contact, but said that didn't constitute battery either. "It was incidental," she said.

At a Wisconsin campaign rally hours after Lewandowski was charged, Trump read Fields' account aloud: "Maybe he touched (her) a little bit, but I didn't see," Trump told the crowd. "It was almost like he was trying to keep her off me, right?"

Fields weighed in on Twitter: "My story never changed. Seriously, just stop lying."

She quit Breitbart shortly after the altercation, saying its editors didn't support her as they tried to maintain their relationship with Trump. Other Breitbart employees also quit.

Aronberg said he talked with Fields and said she was disappointed.

"She wanted a prosecution to go forward," he said.

The prosecutor's announcement came days before the New York primary next Tuesday. Trump hopes New York marks an end to the worst period of his candidacy, a stretch that raised new questions about his policy chops and revealed his campaign's lack of preparedness for a potential delegate fight if the GOP race heads to a contested convention.

Aronberg is a Democrat, a former state legislator who served with Republican Sen. Marco Rubio in Tallahassee and lived in the same dormitory for a time as Texas Sen. Ted Cruz at Harvard Law School. He said he understood the case had garnered international attention, but the political climate did not affect his decision.

He also said he and several members of his office had spoken by phone with Trump — who lives part-time in Palm Beach County — about the case.

"He urged us to do the right thing," Aronberg said. "The conversation we had with Mr. Trump had no bearing on our decision in this case."

-AP