We won’t have to endure too much agonizing over the motive for yesterday’s terrorist attack, as often happens — at least in the media. Not only did Sayfullo Saipov leave notes behind to explain his determination to support radical Islamic terrorism, CBS News reports that he’s bragging about it from his hospital bed. “ISIS will endure,” read one of the notes, a case of toxic wishful thinking:

The suspect in Tuesday’s terrorist attack in lower Manhattan bragged to police about the deadly attack from his hospital bed, saying he would have continued mowing down bikers and pedestrians had he not crashed.

Sayfullo Habibullaevic Saipov, 29, told police he is pleased with his actions and is unapologetic for the attack, sources tell CBS News. One source said Saipov made “no bones” about the attack, which killed 8 people and injured at least 11.

Investigators also discovered 10 to 15 pieces of paper with writing in Arabic praising the Islamic State of Iraq and Syria. One note said “ISIS will endure,” sources say.

In the aftermath, questions are being raised about whether Saipov should have come to the attention of law enforcement earlier. The New York Times reports that Saipov had been “on the radar of federal authorities” as early as two years ago:

As investigators began on Tuesday to look into Mr. Saipov’s history, it became clear that he had been on the radar of federal authorities. Three officials said he had come to their attention as a result of an unrelated investigation, but it was not clear whether that was because he was a friend, an associate or a family member of someone under scrutiny or because he had been the focus of an investigation.

Over the last two years, a terrorism investigation by the F.B.I., the Department of Homeland Security, the New York Police Department and federal prosecutors in Brooklyn resulted in charges against five men from Uzbekistan and one from Kazakhstan of providing material support to ISIS. Several of the men have pleaded guilty. It is unclear whether Mr. Saipov was connected with that investigation.

ABC later played down that report:

MORE: Suspect was never main focus of these investigations and was never subject of his own case file, law enforcement sources tell @ABC.

— ABC News (@ABC) November 1, 2017

However, that investigation has its own problems, such as … one of Saipov’s contacts having disappeared from law enforcement:

The suspected New York City attacker, Sayfullo Saipov, was interviewed in 2015 by federal agents in the Department of Homeland Security Investigations Unit about possible ties to suspected terrorists, but the agents did not have enough evidence to open a case on him, laws enforcement officials tell ABC News.

Saipov’s name and address was listed as a “point of contact” for two different men whose names were entered into the Counterterrorism and Criminal Exploitation Unit’s list after they came to the United States from “threat countries,” one federal official told ABC News.

One of the two men has vanished and is being actively sought by federal agents as a “suspected terrorist.”

Oh goody. It also appears that Saipov had recently been researching ISIS methods without triggering any notice from law enforcement. Despite the rather ad-hoc arrangements of the attack, the Washington Post reports that investigators now believe Saipov had been planning the attack for weeks. His radicalization appears to have been relatively recent, although that might change as more evidence emerges:

Saipov’s notes were handwritten in Arabic and said that “the Islamic State would endure forever,” John Miller, the deputy New York police commissioner for intelligence and counter-terrorism, said at a news briefing on Tuesday.

“He did this in the name of ISIS,” Miller said. “He appears to have followed almost exactly to a T the instructions that ISIS has put out in its social media channels before with instructions to their followers on how to carry out such an attack.” …

“The evidence shows . . . that after he came to the United States, is when he started to become informed about ISIS and radical Islamic tactics,” Cuomo said during an appearance on CNN’s “New Day”, using one of the acronyms for the group. “We have no evidence yet of associations or continuing plot or associated plots, and our only evidence to date is that this was an isolated incident that he himself performed.

Saipov came to the US in 2010; ISIS didn’t emerge until late 2013, when it transitioned from al-Qaeda in Iraq and began to acquire momentum in the Syrian-Iraq frontier. The NYT report includes comments from a Florida woman, herself an Uzbek transplant, who knew him at the time as a happy immigrant:

At one point, Mr. Saipov made his way to Fort Myers, Fla., where he met a fellow Uzbek immigrant, Kobiljon Matkarov, 37. Mr. Saipov was working as a truck driver at the time.

“He was a very good person when I knew him,” he said. “He liked the U.S. He seemed very lucky, and all the time he was happy and talking like everything is O.K. He did not seem like a terrorist, but I did not know him from the inside.”

The process of his radicalization will be a crucial element in the investigation, as any coordination might have more potential terror recruits ready to launch their own “lone wolf” attacks. Was there any direct contact with ISIS recruiters, either privately or through social media? If so, who were those points of contact and communication channels, and can they be reverse-engineered or penetrated to find other potential terrorists? The bonus in this case is that Saipov is still alive to interrogate, although he’s reportedly uncooperative. Except for his grotesque bragging, which is likely to earn him a needle at some point.

In a reminder at just how international the Big Apple is, the FDNY commissioner told the media that six of Saipov’s eight murder victims were foreign nationals:

FDNY commissioner: Of NYC attack fatalities, 6 were citizens of other countries and 2 were Americans https://t.co/NwktvPF5y4

— NBC News (@NBCNews) November 1, 2017

Five of the victims were friends from Argentina, as CBS also reported this morning, in New York for a celebration. They died together on the bike path instead.