A Cambridge man is in custody after tweeting that he’d pay $500 to anyone who killed a federal immigration agent, authorities announced.

Brandon James Ziobrowski, 33, is expected to make his initial appearance on a charge of using interstate and foreign commerce to transmit a threat to injure another person today in U.S. District Court in the Eastern District of New York. He’ll be arraigned in the federal courthouse in South Boston at 3 p.m. next Wednesday.

U.S. Attorney Andrew Lelling, Boston FBI Special Agent in Charge Harold Shaw and Boston Homeland Security Investigations Special Agent in Charge Peter Fitzhugh held a press conference yesterday morning to announce the arrest — and condemn a rise in threats and violence against law enforcement.

“We’ve seen an uptick in attacks on law enforcement officers,” Shaw said, citing examples such as officers shot to death in Weymouth and Yarmouth this year.

Authorities say Ziombrowski — tweeting under the handle @Vine_II and name adobe_flash_player.dmg — wrote on July 2: “I am broke but I will scrounge and literally give $500 to anyone who kills and ice agent. @me seriously who else can pledge get in on this let’s make it work.”

Lelling said there’s no evidence to suggest anyone attempted to take him up on the offer, but the U.S. Attorney did note that two people “liked” the tweet and he had about 400 followers at the time before Twitter suspended his account.

Lelling said his office is not launching a particular initiative based on rooting out this kind of crime, but he wanted to use this case to make a clear statement that he can and will put people behind bars for this type of offense.

“There’s a difference between public debate and intentionally putting others at fear for their lives,” Lelling said. “That line is not obscure, but if the public needs this office to police it, we will do that. I can promise that during my tenure, This office will aggressively prosecute anyone who incites violence against law enforcement officers.”

Lelling made a point of saying multiple times that people can feel free to criticize law enforcement and ICE, which has come under particular fire lately as many on the political left have begun to aggressively lobby to “abolish ICE.” Lelling said threats against the immigration-enforcement agents have increased lately.

“The point of this case is to lay down a marker — there is a line you do not cross,” Lelling said. “The temperature out there has gotten a little too high. The political rhetoric we see has now veered into what we see today.”

Authorities said Ziombrowski has had his Twitter account for nine years, and has ramped up his vitriol over time.

“Extreme anti-U.S. sentiment was also expressed, as well as violent rhetoric regarding guns and numerous references to extreme communist, socialist and anarchist ideologies,” Shaw said.

Lelling said authorities don’t know of any connections Ziobrowski has to political or activist groups.

“He appears to just be some guy living in Cambridge who had strong feelings on the subject,” Lelling said.

The feds allege, "he has repeatedly tweeted his desire to 'slit' Senator John McCain's throat." McCain, 81, a war hero and the Republican Party's 2008 presidential nominee, is battling brain cancer.

Authorites also say Ziombrowski tweeted, "Guns should only be legal for shooting the police like the second amendment intended."

When an ICE field director tweeted that agents put their "lives on the line to arrest criminal aliens," the account identified as Ziombrowski’s tweeted, "Thank you ICE for putting your lives on the line and hopefully dying I guess so there's less of you?"