It was a tense day in the trial of accused Etan Patz murderer Pedro Hernandez. The prosecutor and a key defense witness repeatedly shouted at each other. NY1's Michael Herzenberg filed this report.

It was prosecutor versus former prosecutor in the murder trial of Pedro Hernandez Tuesday.

The Manhattan District Attorney's office tried to paint a star defense witness, ex-assistant U.S. Attorney Stuart GraBois, as a sloppy investigator with an agenda.

"Your tone should be modified!"  GraBois barked at the prosecutor.

Prosecutor Joan Illuzzi-Orbon shot back, "And you should stop yelling at me."

That jousting occurred over testimony that GraBois consulted a psychic when he lead a federal investigation into Etan's death.

GraBois testified for the defense he once wanted someone else to be charged with the killing, so discrediting him is a crucial part of the prosecution’s case that Pedro Hernandez killed Etan.

Grabois said Monday that convicted child molester Jose Ramos told him he was 90 percent sure he picked up Etan and tried to sexually assault him on the day the six-year-old boy vanished in 1979. Ramos claimed his advances were rejected, and he dropped Patz off at the subway.

Illuzzi-Orbon asked GraBois on cross examination if he showed Ramos pictures of Etan to make the confession stronger. GraBois said he couldn't recall.

Etan was carrying a bag filled with matchbox cars and was wearing a hat like this.

GraBois said he couldn't recall if he asked Ramos about that, either, or if he looked into an apparent discrepancy in Ramos' confession.

Ramos said the child was wearing a western style belt buckle.

Etan wasn't.

"His credibility is beyond question," said Hernandez's defense attorney, Harvey Fishbein.

Fishbein thinks GraBois held up well, and that his dogged determination over the years led to Ramos's conviction for molesting other children, even if he didn't find enough to charge Ramos in Etan's death.

"Stuart GraBois should be thanked because regardless of what happens in this case he made sure Jose Ramos stayed in jail his entire life,"  Fishbein said.

Court resumes Thursday with another key defense witness.  A jailhouse informant who is expected to claim Ramos told him sordid details about molesting the boy.