IE 11 is not supported. For an optimal experience visit our site on another browser.

KNOW IT ALL: Monday's Top Stories at NBC News

A look at the leading headlines.
Image: Supporters greet U.S. Democratic presidential candidate Hillary Clinton as she arrives to speak at the University of California Riverside in Riverside
Supporters greet U.S. Democratic presidential candidate Hillary Clinton as she arrives to speak at the University of California Riverside in Riverside, California, U.S. May 24, 2016.LUCY NICHOLSON / Reuters

Good morning. Here are some of the headlines we're following this morning:

Clinton Wins Puerto Rico to Edge Nearer to Nomination

Hillary Clinton crept closer to the magic number of 2,383 delegates needed to clinch the Democratic presidential nomination Sunday, winning the Puerto Rico primary. She is widely expected to secure the Democratic nomination on Tuesday when Democratic voters in six states. Puerto Rico voters faced long lines and confusion over polling stations, many of which had closed since the Democratic primary in 2008. Read more at DECISION 2016.

Trump Stirs More Controversy With Judge Criticism

Donald Trump stirred more outrage over the weekend by standing by claims that a judge's Mexican heritage means he can't render a fair verdict against him and suggesting a Muslim judge might also be biased. The presumptive Republican nominee has attacked U.S. District Judge Gonzalo Curiel — born in Indiana to Mexican-born parents and presiding over a lawsuit involving Trump University — as a "hater of Donald Trump." Republican leadership disavowed the remarks. Read more at DECISION 2016.

'He Was an Ambassador for Humanity': Ali Hailed at Service

Christians and Jews joined Muslims in mourning the death of Muhammad Ali at a packed mosque in the boxing legend's hometown of Louisville, Kentucky, on Sunday night, where he was remembered as an ambassador for all humanity. The three-time world heavyweight boxing champion died Friday of septic shock from natural causes. Ali's body was returned Sunday to Louisville, where a public memorial service is planned for Friday. Read more in U.S. NEWS.

Supreme Court Vacancy Could Impact Key Cases

The U.S. Supreme Court heads into the final month of its term with decisions yet to come on such divisive issues as immigration, abortion, and affirmative action. Those cases could produce major rulings affecting millions of people. But with just eight justices now on the bench, some could end in a modest decision or fizzle out in a four-four tie. "There are blockbuster cases, but we may not get divisive blockbuster rulings," says Tom Goldstein, the publisher of the SCOTUSBlog website and a lawyer who argues before the court. Read more in U.S. NEWS.

Two NPR Journalists Killed in Attack in Afghanistan

A National Public Radio photojournalist and his Afghan translator were killed on Sunday in southern Afghanistan, NPR said in a statement. David Gilkey and his Afghan translator, Zabihullah Tamanna were on assignment with an Afghan army unit when their convoy came under fire and their vehicle was struck by shellfire, NPR said. It said Gilkey and Tamanna were killed; an NPR reporter and producer also traveling with the unit were unharmed. Read more in WORLD.

Soggy Monday for Gulf Coast as Tropical Storm Colin Arrives

A tropical depression churning toward Florida strengthened into Tropical Storm Colin and was headed toward a wide area spanning the Gulf of Mexico to the Atlantic Seaboard, the National Weather Service said Monday morning. MSNBC meteorologist Bill Karins said "exact landfall of Colin will be Monday evening but with a disorganized low end tropical storm, only the history books will care where it crosses the coast because no damage will occur when it does." Read more in WEATHER.

Read How a Heroin Crisis in One City Sparked a Police Revolution

Like many unsuspecting communities, Gloucester, Massachusetts, woke to its heroin problem with a sudden rash of overdoses. Four deaths in three months was catastrophic for Gloucester, a small fishing town that tended to keep its addictions quiet. What happened next put the city at the center of a shift in American policing that could alter the course of the war on drugs: The cops offered addicts help. Read more in U.S. NEWS.

Attention! Meet Miss USA, 1st Lt. Deshauna Barber

The newly crowned Miss USA is a 26-year-old Deshauna Barber, a first lieutenant in the U.S. Army who gave perhaps the strongest answer of the night when asked about women in combat. "As a woman in the United States Army, I think ... we are just as tough as men. As a commander of my unit, I'm powerful, I am dedicated,'' Barber said. "Gender does not limit us in the United States.'' As the winner of Sunday's 2016 Miss USA competition, Barber will go on to compete in the Miss Universe contest. Read more at NBC Washington.