June 12, 2009 -- A son of the 88-year-old white supremacist who allegedly started a shootout at the U.S. Holocaust Memorial Museum is slamming his father's "cowardice" and apologizing to the family of the security guard his dad is accused of killing.

"My father's actions are unforgivable," Erik von Brunn, 32, of Florida, wrote in a statement to ABC News. "I do not expect, nor will I accept forgiveness for what he has done. I realize there is nothing positive to be taken from this incident."

Click here to read Erik von Brunn's full statement to ABC News.

Erik von Brunn's father, James von Brunn, has been charged with first-degree murder in the death of Stephen Tyrone Johns, the museum guard who opened the door for elderly man to let him into the museum.

In apologizing to Johns' family, Erik von Brunn said his father's hatred has tormented his own family for years, as well.

"My father's beliefs have been a constant source of verbal and mental abuse my family has had to suffer with for many years," he wrote. "His views consumed him, and in doing so, not only destroyed his life, but destroyed our family and ruined our lives as well.

"For a long time, I believed this was our family's cross to bear," he added. "Now, it is not only my families lives that are in shambles, but those who were directly affected by his actions; especially the family of Mr. Johns, who bravely sacrificed his life to stop my father.

"I cannot express enough how deeply sorry I am it was Mr. Johns, and not my father who lost their life [Wednesday]," Erik von Brunn said. "It was unjustified and unfair that he died, and while my condolences could never begin to offer appeasement, they, along with my remorse is all I have to give."

Von Brunn, who wrote a book alleging a Jewish plot against civilization, long has been held in some esteem by members of hate groups. He allegedly left behind hate-filled handwritten notes in his car, according to the criminal complaint against him filed in federal court in Washington Thursday.

"You want my weapons -- this is how you'll get them," a note read. "The Holocaust is a lie. Obama was created by Jews. Obama does what his Jew owners tell him to do. Jews captured America's money. Jews control the mass media. The 1st Amendment is abrogated -- henceforth."

To read the entire criminal complaint, click here.

But Erik von Brunn, whose parents divorced years ago, had some words for those who lionize his father.

"For the extremists who believe my father is a hero: it is imperative you understand what he did was an act of cowardice," Erik von Brunn wrote. "To physically force your beliefs onto others with violence is not brave, but bullying. Doing so only serves to prove how weak those beliefs are. It is simply desperation, reminiscent of a temper tantrum when a child cannot get his way. Violence is a cop out; an easy answer for an ignorant problem."

Von Brunn is facing first-degree murder and weapons charges, but investigators and prosecutors are "looking at potential civil rights or hate crimes" charges, Joe Persichini, the assistant director in charge of the FBI's Washington field office, said at a press conference near the museum Thursday.

According to the complaint, video cameras captured the entire incident, from von Brunn double-parking his 2002 red Hyundai outside the museum through the alleged attack.

"As the defendant approached the entrance to the museum, Special Police Officer ('SPO') Steven [sic] Tyrone Jones, who was employed as a security guard for the museum, opened the door for the defendant," the complaint says. "The defendant raised his rifle, aimed it at SPO Johns and fired one time, striking SPO Johns in the left, upper chest area."

Two additional guards returned fire as von Brunn continued through the door and "raised his firearm as if to fire again," the document continued. "The defendant was shot in the face and fell backwards outside the door."

Ambulances rushed von Brunn and Johns to George Washington University Hospital after the incident. Johns died at the hospital of injuries sustained in the attack, and von Brunn remains in critical condition.

Von Brunn allegedly used a .22-caliber rifle, and the complaint notes that three .22-caliber cartridge casings were recovered at the scene, indicating that the suspect fired three shots.

Already a convicted felon for a 1981 crime, von Brunn was prohibited from possessing a gun.

"Obviously, that will be something that will be followed up," D.C. Metro Police Chief Cathy Lanier said at a press conference Thursday.

James von Brunn Described as Angry, Frustrated with the Government

People who know von Brunn described him as a volatile, angry man whose raging prejudices ramped up in recent years because of his frustration with the government and the election of the nation's first black president.

"We thought he was like a pressure cooker, just ready to go off," said one resident of Easton, Md., where von Brunn recently lived.

"We always had the sense though that there was an anger under him," said another acquaintance.

"Yes, I would say that he was crazy," a man added.

John de Nugent, a self-described white separatist who never met von Brunn in person but was in contact with him, said Wednesday's shooting didn't come as a surprise to him.

He had given away his computer, and turned control of his Web site, www.holywesternempire.org, over to someone else, de Nugent said. The site is no longer accessible on the Internet.

"When you hear about people giving away precious things, it makes you think that something bad is going to happen," de Nugent said on "Good Morning America."

"I think at least a year ago, his Social Security was slashed. And he felt that this was a direct result of somebody in the federal government reading his Web site, and punishing him for his politically incorrect opinions," de Nugent said. "I think the election of Barack Obama became a tremendous signal of alarm for him."

"The FBI did not have an open investigation on Mr. von Brunn," said Persichini. "But we were aware of him, and he is known as an anti-Semite and a white supremacist that established Web sites that espoused hatred" against Jews, African-Americans and others.

Persichini said individuals who hold such beliefs are often acutely aware of their rights, and the type of activity or speech that would trigger an investigation.

"Law enforcement's challenge every day," he said, "is to balance the civil liberties of the United States citizen against the need to investigate activities that might lead to criminal conduct."

"No matter how offensive to some, we are keenly aware that expressing views is not a crime, and the protections afforded under the constitution cannot be compromised," he continued, stressing that investigators rely on tips in cases like von Brunn's.

"There has been a significant growth in white supremacist hate groups, on the order of something like 50 percent since the year 2000," director of the Southern Poverty Law Center's Intelligence Project Mark Potok said on"Good Morning America" Thursday. "So, yeah, there is a heating up going on out there, and the Obama factor has been important."

The Escalation of Von Brunn's Rhetoric

Both de Nugent and the Southern Poverty Law Center, which tracks hate groups and their activity across the country, noticed an escalation in von Brunn's rhetoric.

"He was advocating direct action, that the time for talk was over," de Nugent said. "And I think he was pushed over the edge by current events and his own personality."

"His rhetoric really has been heating up. We've seen some evidence of that ourselves," Potok said, referring to a 2007 posting on a white supremacist site attributed to von Brunn that seemed to call for action.

The center said Wednesday that von Brunn had long been associated with neo-Nazis and Holocaust deniers. The group had also flagged his Web site because of its content.

The "politically incorrect opinions" on the site include excerpts of von Brunn's book, "Tob Shebbe Goyim Harog," or "Kill the Best Gentiles."

The book is described on the site as "the culmination of his life's work" and "a new, hard-hitting expose of the 'Jew Conspiracy' to destroy the White gene-pool."

The site also touted von Brunn's military and intellectual accomplishments. The U.S. Navy confirmed Thursday that von Brunn served from 1943 to 1946. A Navy official said he earned several awards and decorations, including recognition for his WWII service.

On his Web site, von Brunn also claimed membership in high-I.Q. society Mensa. The organization confirmed that he was a member 20 years ago, but for less than a year.

The biography also highlights a 1981 incident, described as his attempt "to place the treasonous Federal Reserve Board of Governors under legal, nonviolent, citizens arrest."

Archive media reports from the time of the incident and von Brunn's trial say he armed himself with a revolver, sawed-off shotgun and a hunting knife before he entered the Federal Reserve Board's headquarters.

The incident was reportedly an attempt to focus media attention on the nation's economic woes and high interest rates set by the Fed.

Potok said it's "remarkable that there is a subculture in this country, of literally thousands and thousands of people who believe things like the Federal Reserve Board is really an entity secretly controlled for the benefit of Jewish bankers, etc., etc., etc."

A jury convicted von Brunn on a litany of charges, from attempted kidnapping to assault and possession of a prohibited weapon.

On the site, he claims he was "tried in a Washington, D.C., Superior Court; convicted by a Negro jury, Jew/Negro attorneys, and sentenced to prison for 11 years by a Jew judge." According to Bureau of Prisons records, von Brunn left prison in September 1989.

The criminal complaint said Missouri native von Brunn has for the past two years rented a room in the Annapolis, Md. apartment a son shares with his fiance.

Stephen Johns Remembered as a 'Hero'

Johns had worked at the museum for six years, and has been, along with the other security staff, praised as a hero by museum, law enforcement and political officials.

At Thursday's news conference, museum chief of staff Bill Parsons thanked Johns and all of the other guards for protecting the public.

"We owe a great debt to them," he said.

"Stephen opened that door for the elderly man coming in. He was caring about him," Parsons said, "And he was shot."

"He was a loving father… and he was also my hero," Johns' 14-year-old son, Stephen Jr., said late Wednesday.

The museum remains closed Thursday, and is flying its flags at half-mast in memory of Johns.

ABC News' Ariane de Vogue, Luis Martinez, Tom Giusto and Polson Kanneth contributed to this report.