The source's message delivered by text was short and simple: "I have big news."

Sadie Gurman, a Justice Department reporter, had covered Colorado's first-in-the-nation pot experiment when she was a staffer in Denver, cultivating activists and law enforcement officials as sources. So when she transferred to Washington about a year ago, she had a burning question: When would Attorney General Jeff Sessions, a fierce opponent of decriminalization of marijuana, reverse the Obama administration’s hands-off approach to states that have legalized the drug?

The answer came last week and Gurman had the scoop – long before the competition and hours ahead of the official announcement. Her story earns the Beat of the Week.

Gurman made it known in Washington that pot policy was tops on her priority list. It was the first question she ever asked Sessions.

Gurman had been keeping a close eye on the marijuana issue ever since Sessions was named attorney general, an appointment that had thrown some in Colorado's legal pot industry into a panic. She had written a number of stories about the black market that had flourished in spite of marijuana legalization. Then when she started in Washington, Gurman made it known to everyone that pot policy was tops on her priority list. She began trying to meet people who would be privy to changes Session would make.

It was the first question Gurman ever asked Sessions, and one she would ask officials in all walks of government. In August, she scored an earlier beat by breaking news that Sessions’ own task force failed to provide him with a justification for a crackdown. That opened the door to new sources on the topic. Gurman’s persistence paid off in an even bigger way the night of Jan. 3 when a source texted there was news.

She immediately knew what that meant: Sessions was tearing up the “Cole Memo” that instructed U.S. authorities to generally not interfere with states that legalized marijuana, even if the local marijuana trade violated federal laws.

Gurman worked throughout the night contacting multiple sources for confirmation until she had it nailed down early Thursday morning. The APNewsAlert moved at 8:39 a.m., hours ahead of the official announcement. Most major news outlets used the AP story or scrambled to match it. The New York Times and Washington Post alerted the news at 10:18 and 10:27 a.m. respectively, with both crediting AP with the break in the third paragraphs of their stories.

Given her expertise on the subject and her anticipation that Sessions would act, it was easy for Gurman to quickly write the story.

While other news organizations were chasing her NewsBreak, Gurman was doing a Q&A that helped AP's readers make sense of the confusing change. And pot stocks fell almost as soon as the AP story was out.

NPR contacted Gurman within minutes after the story moved and quickly interviewed her for Morning Edition, the first of several on-air interviews. She also was interviewed for the AP video.

The story was the most-tweeted of the day and topped AP news for the day with over 560,000 interactions and 1,200 customer pickups. Even the competition had to tip its hat: the Washington Post’s Justice Department reporter emailed Gurman that the story was “a really good – and big – get.”

For her persistence and beat on this major change in marijuana policy, Gurman earns this week's $500 prize.