Michael Jackson's eldest son testified on Wednesday (June 26) in the wrongful death lawsuit filed by his family against AEG Live that the late pop star was unhappy with the concert promoter in the run-up to his aborted "This Is It" concert series in 2009.

16 year old Prince is the first member of the Jackson family to testify in the trial. He told the court that he saw his father often get upset on the phone with the AEG Live CEO, but was unable to stand up for himself in disagreements.

Michael Jackson died at age 50 from an overdose of surgical anesthetic propofol while he rehearsed in Los Angeles for a series of comeback concerts in London in 2009.

The "Thriller" singer's mother, Katherine, is suing privately held AEG Live, which was promoting Jackson's "This Is It" concerts, for negligence in hiring Dr. Conrad Murray as his personal physician.

Prince, wearing a dark suit and tie, showed little emotion while testifying until he described his father's death, wh