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KNOW IT ALL: Monday's Top 6 Stories at NBC News

From an unwelcome visitor at the White House to a successful Martian mission, see the stories we're following.
Image: White House Fence
Uniformed Secret Service officers walk along the lawn on the North side of the White House in Washington, Saturday, Sept. 20, 2014. Susan Walsh / AP

Good morning, and happy Monday. Here are some of the stories we're following today:

1. Search continues for missing college student

More than a week after University of Virginia student Hannah Graham went missing, her parents spoke in public for the first time, asking anyone with any information about where their 18-year-old daughter might be to come forward. The community of Charlottesville rallied over the weekend to conduct mass searches throughout the city for the woman, who was last seen after leaving a party on Sept. 13. More than 1,000 volunteers combed the city on Saturday and Sunday, and officials said leads that came out of the widespread search would allow them to pursue a more "targeted" search in coming days. Meanwhile, police have issued an arrest warrant on unrelated charges for a man believed to have been seen with Graham the morning she disappeared. Read more in NEWS.

2. Secret Service investigates White House security breach

The Secret Service is reviewing how Omar J. Gonzalez, 42, was able to make it all the way past the North Portico doors of the White House Friday night before he was arrested. Officials initially said Gonzalez was unarmed, but a law enforcement official told NBC News that Gonzales had a four-inch folding knife on him when he was arrested. The first family was not home at the time of the breach. Gonzalez, an Iraq war veteran, is scheduled to appear in federal court today. Read more in NEWS.

3. Suspected trooper-killer still on the loose

Eric Frein, 31, who is accused of killing Pennsylvania State Police Cpl. Bryon Dickson with a high-powered rifle and injuring another officer, was likely planning his attack for months, maybe years, police said Sunday. As the ninth day of a manhunt for Frein closed, police said they found an AK-47-style assault rifle and several magazines that the fugitive either left behind or stored beforehand. Investigators believe they are closing in on Frein, who was added to the FBI's Most Wanted list earlier in the week. Read more in NEWS.

4. Three Afghan soldiers go missing in Massachusetts

Three officers from the Afghanistan National Army visiting Cape Cod for a military exercise have disappeared. Maj. Jan Mohammad Arash, Capt. Mohammad Nasir Askarzada and Capt. Noorullah Aminyar were last seen at the Hyannis Mall on Saturday evening. According to the National Guard, the soldiers were heavily vetted before coming to the U.S, and the Guard believes the public is not in danger. Read more in NEWS.

5. Huge California wildfire destroys 32 buildings

The "King fire" in Northern California grew to 128 square miles, pushing nearly 3,000 people out of their homes. Ten homes have been destroyed by the flames. Twenty-two other structures have been damaged in the fire, but officials said once assessors can get closer to the damage, that number will likely increase. Rain and cooler temperatures on Sunday helped more than 5,000 personnel fight the fire, which was allegedly started by a suspected arsonist. Read more in NEWS.

6. NASA’s Maven mission enters Mars orbit

What happened to the air and water on Mars? NASA's Maven orbiter entered Martian orbit on Sunday to find out. The Maven traveled 442 million miles over ten months and is expected to study Mars' upper atmosphere for one Earth year. Maven's name comes from an acronym that stands for Mars Atmosphere and Volatile EvolutioN. Read more in SCIENCE.