Four members of the media witnessed his execution.
Moore's case wound its way through the court system for almost four decades, ever since the August 1979 slayings of Reuel Van Ness and Maynard Helgeland, both taxi drivers and Korean War veterans.
"I should (have) led him in the right way to go instead of bringing him down, way down", Moore said. The company makes cisatracurium besylate and potassium chloride, and said it opposes use of its products in executions.
Moore was pronounced dead by the coroner at 10:47am.
Nationwide, an increasing number of pharmaceutical companies have taken legal action against states that use their products in executions, making it increasingly hard for states to obtain the drugs.
The execution drew only about a dozen death penalty supporters and protesters who stood in the rain outside the Nebraska State Penitentiary in Lincoln.
"The 38-year-long journey to this execution further proves what we've been saying all along: The ACLU believes the death penalty in America is a broken process from start to finish and should be abolished nationwide", the group said in a statement.
Prosecutors said that at the age of 21, Moore fatally shot Reuel Van Ness during a robbery with his younger brother, using the money to buy drugs and pornography.
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Belgian website DH.be quoted the defender as saying: "When I hear I've refused to play since I came back from vacation, it's wrong.
State prison director Scott Frakes wrote in an affidavit after the lawsuit was filed that "lethal substances used in a lethal injection execution are hard, if almost impossible, to obtain", detailing his attempts to secure drugs from at least 40 suppliers, according to the Washington Post. No members of the victims' families witnessed the execution.
Moore's execution comes a little more than three years after Nebraska lawmakers abolished the death penalty, only to have it reinstated the following year through a citizen ballot drive partially financed by Republican Gov. Pete Ricketts.
Three of the four substances used in Tuesday's execution had never been used for lethal injections - underscoring the difficulty states across the U.S. have had in obtaining previously employed execution drugs.
Moore also asked forgiveness from his brother.
Moore had been fighting the state's efforts to execute him for years, but he made a decision to stop fighting and reportedly told friends he was ready to die.
The company, Fresenius Kabi, argued that allowing the execution to go forward would harm its reputation and business relationships.
The lawsuit - and Nebraska's claims that it essentially has one narrow window to carry out this lethal injection - speaks to how dramatically the landscape for American capital punishment has transformed since Moore was sentenced.
Oklahoma announced earlier this year it would begin using nitrogen gas to carry out its executions.
The choice of fentanyl for an execution points to a state's desperation to find drugs, experts said.
Moore's execution was the 16th in the United States this year, according to the Death Penalty Information Center. "The people of Nebraska have spoken".