John Rinaldi is accused of stalking and harassment but maintains his innocence, insisting he was just trying to convince Brooke to get involved in the setting up of a children’s charity called The Sandy Hook Center.

However, as he took to the witness stand for the trial in Manhattan, New York, the stress of the situation was clear to see as comedy writer Chris Henchy struggled to control his emotions.

"I don’t want my wife walking out the door and having to look left and right for her safety," he said, according to Fox News. "It was disturbing what he had on his Facebook page, photos of him shirtless, photos of him with kids."

One of the most disturbing incidents Henchy experienced was when Rinaldi sent Shields' publicist a lengthy email in which he referenced a woman who was killed by her stalker.

"Rebecca Schaeffer was an actress in Los Angeles who in 1989 was murdered by a guy named (Robert) John Bardo,” Henchy said. "John was a guy who travelled to Los Angeles, tried to give her gifts of stuffed animals, she rejected the gifts, he found out where she lived, he knocked on her door, she asked him to leave her alone, he came back and shot her.

"For him to make that analogy was extremely disturbing."

Among the other attempts Rinaldi made to contact Shields involved him delivering a box of stuffed animals to Shields' New York townhouse back in 2013, which he said at the time was for her children, Rowan, 13 and Grier, 10.

In 2014, he then approached Henchy to discuss the stuffed animal present, with the producer telling Judge Kevin MCGrath: "He just seemed agitated, excited, somewhat unhinged, there was a nervous energy about him. He told me he had been at my house, and that he thought he’d spooked my wife."

Henchy told Rinaldi to "keep his distance".

The last straw for Shields though was when she headed to a charity event on 5 May 2015, and saw Rinaldi's car parked outside her house, with her signature drawn in the dirt on the windscreen, which the actress described as "beyond creepy".

She then made the decision to go to the police and file a complaint against Rinaldi, alleging that he had camped outside her West Village home, blocks away from his own residence, followed her into a local Starbucks coffee shop, and attempted to talk to her kids while they were out and about.

Shortly after Shields filed the police report, her publicist received the email from Rinaldi.

Defense lawyer Jonathan Stonbely has argued that Rinaldi is "socially inept" and meant no harm with his communication attempts - he was just trying to enlist Shields help to set up his charity.