A prosecutor in George Zimmerman’s murder trial on Tuesday tried to pick apart the statements of a Sanford Police detective who had been called as a prosecution witness a day before but gave testimony that seemed to benefit the defense.

Prosecutor Bernie de la Rionda began by asking the judge to strike from the record a statement Detective Chris Serino made Monday in which he said he found credible Zimmerman’s account of how he got into a fight with Trayvon Martin. De la Rionda argued the statement was improper because one witness isn’t allowed to give an opinion on the credibility of another witness. Defense attorney Mark O’Mara argued it was proper because Serino was vetting Zimmerman’s veracity in his probe.

Judge Debra Nelson told jurors to disregard the statement.

“This is an improper comment,” the judge said. De la Rionda then questioned Serino about his opinion given Monday that he didn’t believe Zimmerman displayed any ill will or spite to Martin. Prosecutors must prove there was ill will, spite or a depraved mind by the defendant to get a second-degree murder conviction.