'Start Here': Synagogue attacked in San Diego, NRA investigated in New York, Joe Biden leads a poll

It's Monday, April 29, 2019. Let's start here.

1. 'Our guy'

The man accused of killing one person and wounding three more with an assault rifle at a synagogue near San Diego also may have set fire to a nearby mosque.

John Earnest, 19, charged with one count of first-degree murder and there counts of attempted first-degree murder after the shooting at Chabad of Poway synagogue, also "is our guy" in a March 24 arson attempt at Dar-ul-Arqam mosque in Escondido, a law enforcement source told ABC News.

The rabbi at Chabad of Poway, ABC News Chief National Correspondent Matt Gutman tells us, was not deterred by Saturday's chaos.

"He actually continued a sermon," Gutman says, "standing on a chair outside, telling people not to be afraid, to be strong."

Tech journalist Laurie Segall also joins "Start Here" to explain the rise of 8chan, a website to which a user claiming to be Earnest posted an anti-Semitic open letter a few hours before the shooting.

"You have this hate moving offline," Segall says, "and in a very visceral and scary way."

2. NRA targeted

The same day Oliver North said he wouldn't seek a second term as National Rifle Association president, New York State Attorney General Letitia James announced her office was investigating the NRA, specifically its finances and status as a tax-exempt non-profit.

"There are curiosities, to say the least, that the attorney general has about whether that tax-exempt status is actually deserved," says ABC News' Aaron Katersky.

3. Poll vault

According to an early poll, in which 35% of Democrats said they're undecided, former Vice President Joseph Robinette Biden led at 17%.

ABC News Political Director Rick Klein joins us today to break down the very latest on the burgeoning Democratic field.

"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:

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From our friends at FiveThirtyEight:

Which picks did NFL mock drafts get most wrong?: With the first round of the NFL draft complete, it appears that the wisdom of the crowds wasn't particularly wise.

Doff your cap:

No spoilers here ... as ABC News' Michael Rothman describes more than a decade of writing about -- and reveling in -- the Marvel Cinematic Universe, the latest entry to which, "The Avengers: Endgame," just shattered box office records with a $1.2 billion opening weekend.

"The highs of watching characters I used to read and love hit the big screen was more than a rush -- it was an affirming feeling that all this time, I was not alone," said Rothman, harking back to his days as a boy waiting in line to buy comic books. "There were millions more just like me who also cherished these stories and adventures."

Read the rest of Rothman's column here.

Marvel Entertainment and ABC News are both owned by the Walt Disney Co.