KNOW IT ALL: Tuesday’s Top Stories at NBC News

Image: File photo of a pickup truck is wrapped around a tree trunk after being thrown there by by a tornado in Moore Oklahoma

A wreckage of a pickup truck is wrapped around a tree trunk after being thrown there by a tornado in Moore, Okla., is an iconic image from the deadly twister that ravaged the town May 20, 2013. Lucas Jackson / Reuters

Good morning and happy Tuesday. Here are some of the top stories we’re following at today:

One year later: Moore rebuilds after devastating twister

A year ago Tuesday, a mammoth tornado tore through Moore, Okla., killing 24 people, injuring 377 and causing an estimated $2 billion in damage. A year later, the town is still trying to recover from the storm, showing great progress in some neighborhoods and making less headway in others. See before-and-after images in NEWS.

NBC News' Janet Shamlian was in Moore a year ago:

Republicans aim high on primary day

Republicans around the country are pleading with voters to turn out in high-profile races that will help determine which party controls the Senate for the final two years of President Barack Obama's tenure. The top races are GOP primaries in Kentucky, Georgia and Oregon. There also are primary contests for governor and some congressional seats in Pennsylvania, Arkansas, Idaho, Georgia and Oregon. Watch a preview in POLITICS.

Meanwhile, Kentucky tea party challenger Matt Bevin's run against Sen. Mitch McConnell has gone to the dogs:

Missouri death-row inmate loses appeal

A federal judge has refused to stop the execution of a Missouri prisoner who argued a rare birth defect would make any lethal injection excruciating and unconstitutional. Dismissing a civil rights lawsuit filed by death-row inmate Russell Bucklew, the court also tossed out his request to have the execution videotaped as evidence of his suffering. He is scheduled to die shortly past midnight Tuesday. Read more in NEWS.

'Brazen' Swiss bank whacked with record $2.6 billion penalty

Hundreds of Credit Suisse employees worked for years to deceive U.S. officials and help wealthy Americans avoid paying taxes through secret offshore accounts, Attorney General Eric Holder said Monday at a news conference announcing that the bank would pay about $2.6 billion. The bank has admitted wrongdoing and made various changes to allow it to move forward in compliance with the law, noted Holder, who dubbed the tax-evasion scheme "brazen." Read more in BUSINESS.

Credit Suisse Gets Largest Tax Penalty Ever at $1.8 Billion 2:24

Oscar Pistorius to undergo month-long psych exam

Oscar Pistorius will be assessed by a panel of mental health experts daily for 30 days to help determine what his state of mind was when he killed his girlfriend, the judge in the case ruled Tuesday. The evaluation will begin May 26. His murder trial was postponed until June 30. Read more in NEWS.

Pistorius to report to mental hospital next week 2:47

California's 'big one' may come in smaller packages: Scientists

A group of scientists in Northern California, looking at the geologic evidence from the last 400 years, says the Bay Area is more likely to get a series of serious quakes rather than “the big one.” If that sounds like good news, it isn't. “A series of earthquakes, 6.7, 6.9, 7.1, 7.4 [on the magnitude scale] within a short period of time ... when you are recovering from one earthquake and are faced with another, it is very, very different and potentially more hazardous,” said geologist David Schwartz. Read more in SCIENCE.