Here’s what you need to know to start the day.

It’s Monday, Dec. 9, 2019. Let’s start here.

1. Deadly shooting investigation

The FBI says it is working on the assumption that last week’s deadly shooting at Naval Air Station Pensacola was an act of terror.

Three people were killed in the attack on Friday morning.

ABC News’ Josh Margolin tells “Start Here” that investigators are also probing a report that the alleged shooter, Saudi national Mohammed Ashamrani, watched mass-shooting vides in the days leading up to the attack.

2. Presentation day

The House Judiciary Committee will hear today from both Democratic and Republican attorneys, who will present evidence gathered in the ongoing impeachment inquiry against President Donald Trump.

ABC News’ Katherine Faulders tells the podcast that Democrats will likely split up the articles of impeachment into three separate “buckets:” “We’re hearing abuse of power, obstruction and bribery.”

3. Investigating the investigators

The Department of Justice inspector general is set to release its findings today after investigating allegations of bias at origins of the Russia investigation.

ABC News Senior Investigative reporter Aaron Katersky explains that at issue for Republicans is the FISA warrant secured by the FBI to open surveillance against former Trump campaign staffer Carter Page: “Republicans have long argued that the application that the FBI used was flawed and tainted with political bias.”

“Start Here,” ABC News’ flagship podcast, offers a straightforward look at the day’s top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, iHeartRadio, Spotify, Stitcher, TuneIn or the ABC News app. Follow @StartHereABC on Twitter, Facebook and Instagram for exclusive content and show updates.

Elsewhere:

‘Likely to rise’: At least five people were killed and many more remain missing after a volcano erupted on a small island in New Zealand on Monday, officials said.

‘Never a dull moment’: A live grenade was found in a dresser donated to a North Carolina thrift store.

‘As much transparency as possible’: Senator Elizabeth Warren made around $1.9 million in compensation from private legal work dating back to 1985, according to documents released Sunday night.

‘Don’t trust everybody’: A San Antonio man has been arrested for allegedly assaulting his girlfriend and carving his name on her forehead with a knife.

From our friends at FiveThirtyEight:

‘North Carolina’s new House map’: It doesn’t get a lot of attention next to the presidential race, but Republicans have a fighting chance to retake control of the U.S. House next year.

Doff your cap:

The longtime puppeteer behind beloved Sesame Street characters Big Bird and Oscar the Grouch, Caroll Spinney, has died at age 85, the Sesame Street Workshop announced in a statement.

Spinney spent five decades with Sesame Street, working with legendary puppeteer Jim Henson at the start of his career.

“Caroll Spinney gave something truly special to the world. With deepest admiration, Sesame Workshop is proud to carry his memory – and his beloved characters – into the future,” the workshop announced in a statement. “Our hearts go out to Caroll’s beloved wife, Debra, and all of his children and grandchildren.”

“Caroll Spinney’s contributions to Sesame Street are countless. He not only gave us Big Bird and Oscar the Grouch, he gave so much of himself as well. We at Sesame Workshop mourn his passing and feel an immense gratitude for all he has given to Sesame Street and to children around the world,” said Sesame Street co-founder Joan Ganz Cooney in a statement.