ST. PETERSBURG, Fla. — One of the last person to see 5-year-old Pheobe Jonchuck alive was on the stand Friday during the John Jonchuck murder trial. 

John Jonchuck's attorneys are trying to prove he was insane when he dropped his daughter off the approach of the Skyway Bridge to her death on Jan. 8, 2015. 

John Jonchuck's mother testified Friday about the days before her grandchild's death. 

Wiping tears from her eyes, Michele Jonchuck talked about the behavior of her son before he killed Phoebe. She described the occasion of John telling her Phoebe's eyes looked possessed and that she wasn't Phoebe anymore.

But it was during the prosecutor's questioning that Michele Jonchuck broke down. 

The prosecutors were trying to prove John Jonchuck was being vindictive and would do anything not to lose custody of his child. 

"I never really thought that he would ever do anything to hurt his daughter because he loved his daughter," Michele said.

That's when the prosecutor pressed, saying John did not want Phoebe's mother and her new boyfriend to get custody of the girl...he also asked Michele about when John told her he was "going to f--- up her life." 

"...and a few days left he murders her?" 

A crying Michele answered yes.

Michele also talked about her son being on medication as far back as 2013. When asked how she knew he was on medication, she said because he was acting normal, to the best of her ability to know. 

Psychologist takes the stand

Later in the afternoon, psychologist Dr. Scot Machlus testified for the defense. He said he interviewed Jonchuck after authorities took him into custody.

“When I saw him, he was naked in the middle of his cell,” Machlus said. "I tried to engage him to get information from him and being able to conduct an interview with him. He did not respond to my questions."

"He either mumbled or didn’t respond it all," Machlus explained. "It was incoherent the things he was saying.”

During his testimony Machlus showed jurors video of Jonchuck being interviewed by a detective.

“It’s almost like — I’m not being weird — it’s like, this is a conspiracy,” Jonchuck tells the detective. “I went looking for answers. I always had problems knowing who I was and what my purpose was.”

Machlus said the video shows Jonchuck had clear signs of paranoia with grandiose delusions and religious preoccupations. 

At one point in the video, Jonchuck began to refer to his daughter Phoebe while speaking with detectives on the video.

“Is Phoebe OK?” Jonchuck asks.

The detective says, “Phoebe, who’s that?”

After a long pause, Jonchuck lifted his head in the video and said, “Phoebe was my daughter.” Then he asks again if she is OK.

Machlus diagnosed Jonchuck with bipolar disorder with psychotic features.

The trial will take a break Monday. Prosecutors will have their opportunity to cross-examine Machlus when proceedings resume on Tuesday.