Kevorkian had wanted Melody and Terrence Youk's testimony to provide insight into his intent for injecting the 52-year-old Lou Gehrig's disease patient with a fatal dose of chemicals last September.

In her Thursday morning ruling, Judge Jessica Cooper told Kevorkian that the arguments in his written motion filed Wednesday applied more to his opposition to Michigan's ban on assisted suicide than to his case. Judge Cooper told Kevorkian that his arguments should be addressed in the Michigan Court of Appeals.

"I'm only here to serve as a referee," Judge Cooper said in court. "I cannot tell you how to try your case and make legal arguments that would make your evidence admissible. But your arguments apply more to the law and not the facts of the case and are not relevant to the trial."

After Kevorkian rested, court went into recess. Closing arguments are expected later Thursday morning.

Kevorkian said that he became involved in Youk's death to relieve his suffering and that relieving his patient's pain was his duty as a dedicated physician.

On Tuesday, prosecutors objected to the testimony of Youk's relatives, saying that the Youks' assessment of Kevorkian's frame of mind was hearsay and would also refer to Youk's pain and suffering, evidence that is inadmissible at the murder trial. Prosecutor John Skrzynski also suggested that the testimony would suggest a consent defense, which is not a legal defense under Michigan law. Skrzynski said the Youks' testimony would generate sympathy for the alleged victim and implicitly condone Kevorkian's actions.

In court papers filed Wednesday morning, Kevorkian, with the help of his legal advisers David Gorosh and Lisa Dwyer, argued that Melody and Terrence Youk should be allowed to testify about their discussions with Kevorkian during their initial meeting. Kevorkian's motion said Youk's relatives' desire to ease his pain would illustrate the retired pathologist's motives in the case.

"This testimony is not being offered to illustrate that Melody and Terry Youk, in fact, had no intention for defendant to kill Thomas Youk," the court papers said. "Furthermore, the testimony is not being offered to illustrate a legal defense of consent or euthanasia to the jury. This is not testimony that will be used to illustrate a point of view. Rather, it is testimony that is offered to illustrate the factual effect that such statements had on Dr. Kevorkian."

Outside the presence of the jury Wednesday, Melody claimed that when she, Thomas and Terrence initially approached Kevorkian, the words "kill" and "murder" never came up. She insisted that Kevorkian only wanted to relieve Thomas of his suffering, not murder him.

"What we hoped might be accomplished is that you would help us bring an end to his situation," Mrs. Youk said. "The word 'kill' never came up. The conversations focused on relieving Tom's suffering. Murder never appeared in our conversations ... that was not our goal."

Kevorkian was originally charged with murder, assisted suicide, and delivery of a controlled substance, but prosecutors dropped the assisted suicide charge to prevent the defense from presenting evidence about Youk's pain and suffering. In a pre-trial hearing, Judge Cooper ruled that evidence about Youk's condition was relevant to assisted suicide but not murder.

Michigan prosecutors believe they proved Kevorkian's alleged intent to kill Tuesday after playing the videotape of Youk's death. In the edited and unedited tapes shown to jurors, Kevorkian is shown having a weak and barely intelligible Youk sign consent forms for his assisted death.

Prosecutors also showed Kevorkian's "60 Minutes" interview with Mike Wallace in which he explained his reasons for submitting the tapes and asking the CBS program to show it to a national audience.

Youk died Sept. 17, approximately three weeks after Michigan enacted a law making assisted suicide a felony punishable by up to five years in prison. Kevorkian was charged with first-degree murder after "60 Minutes" showed the tape to a national audience on November 23.

Court TV's Bryan Robinson contributed to this report.