They called him “the Clown.” But on the day a judge sent Joseph Lombardo to prison for the rest of his life, a prosecutor said the notorious Chicago Outfit killer had “a certain callousness.”

Already, he had been convicted of the brutal 1974 murder of a man he described as a friend — a man who had named his son after Lombardo himself. Decades later that son, Joseph Seifert, recalled in court how, as a 4-year-old, he watched masked men kill his father.

Joseph Seifert said he “stood frozen in the middle of chaos and watched as men viciously beat, shot my father in the front office, his blood splattered the walls and the floor.” But Lombardo later told a judge, in his raspy voice, “I did not kill Danny Seifert.”

Lombardo, 90, died Saturday, according to federal prosecutors.

Few details were available Sunday about the death of the notorious mobster. Assistant U.S. Attorney Amarjeet Bhachu announced Lombardo’s death in a one-page court filing that read “the defendant, Joseph Lombardo, died on or about October 19, 2019.”

Federal Bureau of Prisons records still listed Lombardo as an inmate at the federal supermax prison in Colorado.

In a lengthy piece of correspondence filled with typos and misspellings and filed in federal court in July, Lombardo complained, “Im 90 years old, on 12 pills a day, had 32 radiation on my throat cancer, had 4 stents in my arterys at 4 different times, had gul bladder removed, had 4 polips cut, all my teeth are gone, Ive waited 6 months for dentures they tell me I have to wait my turn.”

He also wrote of “positive proof” of his innocence in the murder of Daniel Seifert. A federal jury eventually pinned the brutal, execution-style murder on Lombardo. Federal prosecutors say it was committed in front of Seifert’s wife, who was holding her young son in her arms.

“We were friends until he was killed,” Lombardo wrote earlier this year.

Lombardo was a colorful character famously photographed holding a copy of the Chicago Sun-Times over his face — a hole cut out for his eyes — as he walked out of court in 1981. Defense attorney Joseph “The Shark” Lopez, who represented Frank Calabrese Sr. in the landmark Family Secrets mob trial, remembered Lombardo as “very knowledgeable” and pleasant during the famous prosecution.

But the filing of that indictment made Lombardo a fugitive, and the FBI wound up offering a $20,000 reward in 2005 for information leading to his arrest. Lombardo was arrested in January 2006 after dentist Pat Spilotro — the brother of slain gangsters Anthony and Michael Spilotro — turned him in.

Lombardo wound up taking the stand at trial, facing questions about the 1974 murder of Daniel Seifert. Lombardo had purportedly learned his once-close friend was going to testify against him in federal court on a Teamster pension fund fraud case. His crew then tried to handcuff the Bensenville businessman and take him away.

Seifert got free and ran off.

“Then you had your crew chase him down and shoot him down, isn’t that true, sir?” Assistant U.S. Attorney Mitchell Mars asked Lombardo in court.

“That’s not true, sir,” Lombardo said.

Lombardo denied knowing Seifert was going to be a witness against him. And rather than being a mob boss, Lombardo made himself out to be more of a mob gofer. He contended he only acted like a mobster to collect money.

“That was a good role for you, wasn’t it Mr. Lombardo?” Mars asked.

“Yeah, like James Cagney, Edward G. Robinson,” Lombardo said.

“And Joe Lombardo,” Mars cut in, adding, “member of the Outfit.”

“No,” Lombardo said.

“Capo of the Grand Avenue crew,” Mars said.

“No,” Lombardo insisted.

On the day Lombardo received his life sentence, he told U.S. District Judge James Zagel, “I was not given a fair trial.”

“And now, I suppose, the court is going to sentence me to life imprisonment for something I did not do,” Lombardo said. “I want the court and the Seifert family to know that I did not kill Danny Seifert, and also did not have anything to do with it before, during or after.”

But Assistant U.S. Attorney T. Markus Funk said that day in 2009 that Lombardo “had 30 years in which he was not held accountable.”

“Mr. Lombardo is a mobster,” Funk said. “He’s an Outfit member. He is an Outfit boss with no remorse. He has shown no remorse.”

Finally, when it came time to hand down the sentence, Zagel told Lombardo he showed “some balance, some judgment and, I think, based on the evidence before me, some ability to charm people.”

“But I find that that’s really only the surface,” Zagel said. “In the end, we are judged by our actions, not about our wit or our smiles.”

“In cases like these, the things that matter most are the worst things we do,” Zagel said. “And the worst things you have done are terrible.”