The person sending pipe bombs to Democratic politicians still remains loose — and apparently bold or insane enough to plant more. Early this morning, a Tribeca worker found a strange manila envelope outside the Greenwich Street address for Robert De Niro’s restaurant and film production company. It bore the hallmarks of the earlier packages, right down to Debbie Wasserman Schultz’ return address.

The New York police department is investigating it, but clearly this domestic terrorist isn’t through yet:

A building worker noticed the suspicious package around 4 a.m. Thursday and called authorities, the official said.The package was found at 375 Greenwich Street, the site of the restaurant Tribeca Grill and the offices of De Niro’s Tribeca Films. There was no need to evacuate because the building was empty, police said.

The package was addressed to De Niro, a frequent critic of President Donald Trump, a law enforcement official said, noting that the envelope is similar to the ones found Wednesday, including a return address that belonged to Florida Rep. Debbie Wasserman Schultz.

CNN also reported that police believe the device inside to be similar to the others, based on an X-ray of the envelope. That puts it in the same spree as those found yesterday and overnight, including two sent to Maxine Waters. Law enforcement believe another is in the distribution chain for Joe Biden as well.

Presumably this got left after the discovery of other packages, as De Niro’s restaurant would have been open for business until well into the night. If it had been left before yesterday morning, it would have been noticed yesterday as well. That means that the mad bomber-wannabe is still active, still seeking targets, and almost certainly is located in New York City or very close to it. That matches up with what we knew yesterday; the package addressed to CNN had stamps but no cancel marks on them, suggesting that the package had been hand delivered rather than sent in the mail like some of the others.

So what’s the point of these packages? None of the bombs have detonated, and it’s an open question as to whether they ever were intended to be detonated. Plenty of armchair investigators have pointed out apparent deficiencies in design to suggest the whole thing is a hoax, even though actual investigators still haven’t said anything about the issue.

Some people are starting to see wheels within wheels. On Fox this morning, Judge Andrew Napolitano wondered, “Is it a stunt? Is it a dry run? Is it intended to lull us into some false sense of security?”

It’s more basic and simple than that. This is domestic terrorism, designed to intimidate people into silence. The threat itself is terrorism even if the bombs never go off. We don’t know the motive or the perp yet, so just who is intended to be silenced — beyond these specific victims — is still unknown. It’s pointless to speculate on motive and the political identity of the perp until he or she is found, because it’s easy to bend this in any number of ways in order to condemn one side or another in the absence of evidence, and that’s how conspiracy theories germinate and take root. Hard pass.

One point we should emphasize, as always: the person responsible for these attacks/threats is the person who made them. It’s not the media, it’s not Donald Trump or Maxine Waters, it’s not any of the political betes noires or usual suspects. And when we find him, we should have a room set aside in Florence, Colorado for him to spend the rest of his life reflecting on his crimes, which will remain his and his alone.

Update: As expected, the package sent to former VP Joe Biden has been intercepted: