Joe Jackson says he believes Dr. Conrad Murray is "a fall guy" in a conspiracy and that son Michael was murdered.
Jackson, who sat in a courtroom to hear Murray plead not guilty to a single charge of involuntary manslaughter in his son's death last summer, said the district attorney should have been harder on Dr. Murray.
"My son was murdered and all I am after is justice," said Jackson.
A Los Angeles judge set bail at $75,000, despite arguments from the prosecutor that Murray is a flight risk and needs a higher bail. Murray posted the bond and was released several hours later.
Michael Jackson's family, including his parents, four of his brothers and one sister, filled the first two rows of the small courtroom.
"I was looking for justice, and justice, to me, would be a murder charge," Joe Jackson told King.
Prosecutors charged Murray, who was Jackson's personal physician, with causing the pop star's death "without malice" by acting "without due caution and circumspection."
Brian Oxman, Jackson family spokesman and attorney, said the charges do not reflect the severity of the crime.
La Toya Jackson has also released a statement, agreeing with her father.
"Michael was murdered and although he died at the hands of Dr. Conrad Murray, I believe Dr. Murray was a part of a much larger plan," she said.
"There are other individuals involved and I will not rest and I will continue to fight until all of the proper individuals are brought forth and justice is served."