Canadian Parliament. Ottawa. shooting. gunman

(CNN) -- A day after a gunman killed an army reservist in the Canadian capital of Ottawa, many questions remain.

Why did he shoot? Why did he target Nathan Cirillo? Is he connected to the militant group ISIS? Here's a list of what we know -- and don't know -- in the Ottawa shooting.

THE SHOOTER:

What we know: The alleged gunman was born Michael Joseph Hall in Canada, and changed his name to Michael Zehaf-Bibeau, authorities say. He was 32 years old according to court documents.

He was a Canadian citizen who may have had dual Libyan citizenship as well, Royal Canadian Mounted Police Commissioner Bob Paulson said.

Zehaf-Bibeau had criminal records indicating infractions related to drugs, violence and other criminal activities, police said.

His father is a Quebec businessman and his mother works in Canada's Immigration and Refugee Board, according to the Globe and Mail newspaper. The parents are divorced.

What we don't know: Why he changed his name, but two sources told CNN that he converted to Islam. While ISIS militants have stepped up recruitment efforts in Canada, there's no indication so far that the attacker was part of them.

THE MOTIVE:

What we know: Authorities said Zehaf-Bibeau had been applying for a passport and hoped to travel to Syria. His passport had not been revoked, as earlier stories have said.

"I think the passport figured prominently in his motives," Paulson said. "However, we have not come to ground completely on his motivations for this attack. But clearly, it's linked to his radicalization."

Was Zehaf-Bibeau a jihadist? He had "connections" to jihadists in Canada who shared a radical Islamist ideology, including at least one who went overseas to fight in Syria, multiple U.S. sources told CNN.

But Canadian Foreign Minister John Baird said there is "no evidence at this stage" he was linked to jihadists.

What we don't know: The motive. And with the gunman's death, it may never be known.

ACCOMPLICES:

What we know: Ottawa Mayor Jim Watson said thegunman was acting alone. "It appears there was just one shooter, and that shooter is dead," he said.

What we don't know: Whether he had any ties to any group or groups.

"In the days to come, we will learn more about the terrorist and any accomplices he may have had, but this week's events are a grim reminder that Canada is not immune to the types of terrorist attacks we have seen elsewhere in the world," Prime Minister Stephen Harper said.

THE VICTIM:

What we know: Nathan Cirillo was the strong, smiling type. The Canadian army reservist could look the part of the intimidating soldier, but loved snuggling with his dog, enjoying music or joking with friends. He was part of the Argyll and Sutherland Highlanders, a reserve unit of the Canadian army.

His uncle, Jim Cirillo, told CBC News that his father is in Costa Rica and might not yet know about his son's death.

What we don't know: Why the gunman shot Cirillo in the back -- "in cold blood," as Harper put it, while he stood guard at Canada'sNational War Memorial.

THE HERO

What we know: Kevin Vickers, sergeant-at-arms of Canada's House of Commons, is credited with bringing down the gunman. "Kevin is definitely a hero," said Matt Miller, the Vancouver Observer's parliamentary bureau chief, who was in his office just above the shooting.

What we don't know: Details on how he stopped the gunman.Several officers had weapons drawn, and most of the dozens of shots aimed at the gunman appeared to have been fired by officers.

THE SECURITY:

What we know: Shortly after the shooting at the memorial, a gunman entered the nearby building on Parliament Hill. Gunfire first erupted in the building's foyer. Then a second round of shooting happened about a minute later in a hallway or near the entrance to the Parliament's library.

Another disturbing incident occurred Thursday. As the Prime Minister and his wife laid a wreath in memory of Cirillo, a man yelled and wrapped a white scarf around his face. Police quickly subdued him.

What we don't know: Why the security agencies at the Parliamentdid not tighten security after Ottawa police received a 911 call at nearby National War Memorial. We also don't know how the gunman slipped past the metal detectors and into the building.

    More than 700 years after William Wallace died fighting for Scottish independence, and more than 300 years after Scotland and England came together in a United Kingdom, a new agreement could lead to an independent Scotland.

British Prime Minister David Cameron and his Scottish counterpart, First Minister Alex Salmond, signed a deal in Edinburgh, Scotland, on Monday paving the way for Scots to vote on independence from the United Kingdom, Cameron's office announced on Twitter. The referendum, expected to be held in 2014, would allow Scots a straight yes-or-no vote on staying in the union.

The "Yes Scotland" campaign launched in May, trying to "build a groundswell of support for an independent Scotland," with the backing of several famous Scots, most notably actor Sean Connery. Salmond and his Scottish National Party (SNP), which holds power in the Scottish parliament, have pushed for the vote.

A survey released last week by TNS-BMRB showed that only 28% of Scots favor leaving the United Kingdom.

That's somewhat in line with an Ipsos MORI poll of 1,002 Scots, taken in late August, that showed sharp political differences within Scotland. That survey showed that more than 60% of SNP supporters desire full independence. However, only about a third of all the Scots polled wanted to break away from the United Kingdom.

Some detractors have expressed concern about Scotland's economic viability as an independent state. But oil from the North Sea, off the Scottish coast, has enriched the United Kingdom for decades. And the SNP, on its website, says independence "could create an environment where our existing and new private industries can grow more easily," and the party touts a country that retains the British pound, while its future European Union membership creates the benefits of "open borders, shared rights, free trade and extensive cooperation."

Cameron has vocally opposed Scottish independence. In February, he said he was "100% clear that I will fight with everything I have to keep our United Kingdom together," since an intact United Kingdom, consisting of England, Scotland, Wales and Northern Ireland, "is stronger, safer, richer and fairer."

In medieval times, Scotland fought for freedom from England, which Mel Gibson dramatically depicted in his Academy Award-winning movie "Braveheart." Not long after Wallace died in the early 1300s, Robert the Bruce led Scotland to independence, and it remained an autonomous nation until the Act of Union joined Scotland and England in 1707.

The United Kingdom returned some autonomy to Scotland, Wales and Northern Ireland, and gave them the right to form their own parliaments, in the late 1990s.

Ferguson, Missouri, police Officer Darren Wilson, in his first interview since he fatally shot unarmed teenager Michael Brown, said he's not tormented by that fateful encounter on a street in suburban St. Louis last summer.

"I don't think it's haunting," Wilson told ABC News on Tuesday. "It's always going to be something that happened. The reason I have a clean conscience is that I know I did my job right."

Repeating what he told a grand jury investigating the shooting, Wilson said Brown reached into his police vehicle and grabbed for his gun. He feared for his life, he said.

It all started when Wilson asked the teenager to move out of the middle of the street, the officer told ABC's George Stephanopoulos. Brown walked over to his car and pushed the door back as Wilson tried to get out, the officer said.

"As I looked back at him, punches started flying," Wilson said in the interview, which aired Tuesday night. "He threw the first one and hit me in the left side of my face."

Wilson doesn't know how many times he got hit.

"I just know there was a barrage of swinging and grabbing and pulling for about 10 seconds," Wilson told ABC. "I reached out my window with my right hand to grab on to his forearm."

Wilson said he wanted to move Brown away.

"I just felt the immense power that he had. And then the way I've described it is, it was like a 5-year-old holding onto Hulk Hogan. That's just how big this man was," Wilson said. "He was very large, very powerful man."

Wilson is 6-foot-4 and 210 pounds; Brown was the same height and weighed nearly 300 pounds.

Brown unleashed another punch and struck the officer in his face, Wilson said.

"How do I survive," Wilson recalled thinking. "I didn't know if I'd be able to survive another hit like that."

Wilson reached for his gun and told Brown to back off or he would shoot, the officer said.

"You're too much of a (word bleeped) to shoot me," Wilson said Brown told him, before grabbing the top of the officer's gun.

Wilson tried to squeeze off two shots but the gun jammed twice.

Brown, he said, tried to reach the trigger guard to shoot Wilson. Wilson got a shot off on his third attempt, he said.

"He gets even angrier," Wilson said. "His aggression, his face, the intensity just increases. He comes back in at me again."