Colin Kroll, the co-founder of Vine and HQ Trivia, was found dead Sunday inside his New York City apartment. He was 34.

Kroll was discovered by police officers after his girlfriend called and asked for a wellness check, CNN reports. The cause of death has not yet been determined.

HQ Trivia, a trivia game app, was launched in 2017. Kroll became CEO of HQ Trivia's parent company, Intermedia Labs, earlier this year after his business partner Rus Yusupov was forced out, Recode reports. Recently, Kroll was accused by an HQ Trivia employee of "inappropriate and unprofessional behavior;" the matter was investigated and "yielded no concerns," the company told Recode. Catherine Garcia

Before he fought to keep his tax returns private, President Trump wanted to release them, in order to show the world how smart he was for lowering his taxable income, a former adviser told CNN.

Sam Nunberg served as Trump's political adviser from 2011 to August 2015, and said that during a lunch with Trump in 2013, he said he would be fine with his tax returns being released as part of a presidential bid. Nunberg, who did not see the returns himself, told CNN Trump "thought he could defend the return. I inferred from the conversation that he believed that it was a lower number and he'd look savvy." Another one of Trump's former senior advisers joined the pair for lunch, and corroborated Nunberg's account.

In May 2014, Trump declared on Irish television that he would "absolutely" release his tax returns if he decided to run for office, but Nunberg said that six months later, he talked him out of it. During a meeting, he told Trump that under federal election rules, all he had to do was release a broad financial statement, and could leave the tax returns under wraps. Nunberg told CNN he thought this would protect Trump from opponents who could find something explosive in the tax returns. Trump was fine with this, Nunberg added, because "he wanted to look rich rather than smart."

Trump wouldn't announce he was entering the race for another eight months, and he went on to become the first nominee of a major party not to release their taxes in more than three decades. The president's tax returns are now the focus of several legal challenges, and Trump lost an appeal last week to keep House Democrats from subpoenaing his returns from his longtime accountant. Catherine Garcia

Badlands National Park in South Dakota has expanded its bison range, a move that will "contribute to the health and genetic integrity of the herd and continued health of the prairie," the park said.

The bison now have an additional 22,000 acres of grazing land, for a total of 80,193 acres. The park itself is 244,000 acres, with about 1,200 bison calling it home. On Friday, four bison were moved to the new range, returning to the area for the first time in 150 years.

New fencing and cattle guards were installed in the range, thanks to $743,000 in public and private donations. Due to the expansion, visitors will have "more opportunities for viewing, photographing, and learning about bison in their native habitat on the badlands' iconic and stunning landscape," the park said. Former President Barack Obama named the bison the national mammal in 2016. Catherine Garcia

Moving up from the south, Syrian government troops seized several towns in the northeastern part of the country on Monday, one day after reaching an agreement with the Kurdish-led militia that has held control of the area for several years.

The Kurds and Syria reached the deal after President Trump pulled back U.S. troops from the border, giving Turkey the opportunity to invade Syria and launch an assault on the Kurds. The Kurds and United States worked together to fight the Islamic State in Syria, and the Kurds took control over territory lost by ISIS. After the U.S. retreat, the Kurds turned to the Syrian government for added protection against Turkey. Turkish President Recep Tayyip Erdogan considers the Kurds terrorists.

Syrian government forces were able to take control of multiple towns from the Kurds, including Taqba, which has a hydroelectric dam on the Euphrates. Kurdish fighters spent Monday battling Turkish troops and allied Syrian militias in the border towns of Ras al Ain and Tal Abyad. The recent developments are viewed as victories for Syrian President Bashar al-Assad, who counts Russia and Iran as his allies.

Complicating matters is the fact that the U.S. has about 50 tactical nuclear weapons stored at the Incirlik Air Base in Turkey, 250 miles from the Syrian border. Two U.S. officials told The New York Times that over the weekend, State and Energy Department employees were reviewing plans for getting the weapons out of Turkey. They are "essentially Erdogan's hostages," the Times says, and moving them from Turkey would basically end the alliance between the United States and Turkey. Leaving them is just as problematic, as it puts the weapons and U.S. in a vulnerable position. Read more at The New York Times. Catherine Garcia

Former National Security Adviser John Bolton was so alarmed by a White House–linked effort to pressure Ukraine to investigate Democrats, he told aide Fiona Hill to alert the National Security Council's chief lawyer, Hill told House impeachment investigators in her 10-hour deposition on Monday, The New York Times and The Wall Street Journal report. Specifically, Bolton told Hill, the top NSC staffer on Russia and Eurasian affairs, to notify White House lawyers that Rudy Giuliani, White House acting Chief of Staff Mick Mulvaney, and U.S. Ambassador Gordon Sondland were running a rogue operation, the Times reports.

"I am not part of whatever drug deal Sondland and Mulvaney are cooking up," Bolton reportedly told Hill to relate to the lawyers, after a heated July 10 meeting with Sondland, the U.S. ambassador to the European Union and a key player in the Ukraine pressure campaign, and Ukrainian officals. Before that meeting, Hill reportedly testified, Bolton told her that "Giuliani's a hand grenade who's going to blow everybody up." Giuliani, President Trump's personal lawyer, is now under federal criminal investigation for his work in Ukraine, the Journal reported Monday. Sondland is scheduled to be deposed on Thursday.

House investigators are now trying to decide whether to question Bolton, The Washington Post reports.

Hill also testified that he had strongly opposed Giuliani's successful push to have Trump remove America's ambassador to Kyiv, Marie Yovanovitch, who had a reputation for fighting corruption in Ukraine. "I don't know Fiona and can't figure out what she is talking about," Giuliani told the Post on Monday night, adding that he believes she was out of the loop when it came to Ukraine, at least compared with Sondland. "She just didn't know," Giuliani said, reiterating his assertion that he was working on orders from the State Department. Peter Weber

Update, 12:47 a.m.: This article has been updated based on a clarification by the Times:

A Fort Worth, Texas, police officer who shot and killed a woman inside her home early Saturday was charged with murder on Monday, shortly after he resigned from the force.

The former officer, Aaron Dean, is being held at the Tarrant County Correction Center, Fort Worth Police Sgt. Chris Daniels said. The woman, 28-year-old Atatiana Jefferson, was playing video games with her 8-year-old nephew when she was shot. A neighbor had noticed Jefferson's front door was slightly open and called the police department's non-emergency line, asking them to do a wellness check. Body-camera footage released by the police department shows an officer shining a flashlight into the house, then yelling, "Put your hands up, show me your hands," before firing one shot.

The white officer shooting a black woman inside her home caused immediate outrage in Fort Worth, and Daniels had a message for all concerned. "To the citizens and residents of our city, we feel and understand your anger and your disappointment and we stand by you as we work together to make Fort Worth a better place for us all," he said. Jefferson's older sister, Ashley Carr, said Atatiana was "simply going on along with her life, living a law-abiding citizen's peaceful life, and she was killed by a reckless act of a Fort Worth police officer. There is simply no justification for his actions." Catherine Garcia

During her testimony before House lawmakers on Monday, Fiona Hill, President Trump's former top Russia adviser, said that Rudy Giuliani wanted to see certain things happen in Ukraine in order to benefit Trump, so he went around U.S. officials and career diplomats, a person familiar with the matter told The Washington Post.

Hill met with lawmakers from the three House committees investigating Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky. Throughout her 10-hour, closed-door testimony, she shared her concerns over Giuliani's role in Ukrainian foreign policy, the Post says. Hill was a member of the National Security Council, but left one week before Trump's call with Zelensky.

Hill also reportedly praised Marie Yovanovitch, the former ambassador to Ukraine, and told lawmakers she was angry when Yovanovitch was removed in May, after Giuliani pressured Trump to recall her from the post. Last week, Yovanovitch testified as part of the impeachment inquiry, and said Giuliani and some of his Ukrainian allies saw her as a threat, standing in the way of their political and financial interests. Catherine Garcia