Prison officials said they found no obvious signs of assault. Source

Caucuses get underway in Iowa today; Tight democratic race in Iowa caucuses. Source

President Trump’s impeachment trial is expected to come to an end Wednesday. House managers and the president’s legal team will give their closing arguments today. CBS News White House correspondent Weijia Jiang and former Justice Department national security prosecutor Joseph Moreno joined CBSN with more on what to expect. Source

Iowa Democrats start caucusing at 7 p.m. local time tonight. A new CBS News Battleground Tracker shows Senator Bernie Sanders and former Vice President Joe Biden are in a dead heat in the state. Senior Washington correspondent Major Garrett and CBS News special correspondent Alex Wagner join CBSN from Des Moines. Source

The last CBS News Battleground Tracker before the Iowa caucuses has former Vice President Joe Biden and Senator Bernie Sanders tied at the top. “CBS This Morning” co-anchor Tony Dokoupil reports from Des Moines, and CBSN political reporter Caitlin Huey-Burns chats with Radio Iowa news director O. Kay Henderson about the race. Source

More than two-thirds of Americans qualify to file their tax returns for free, but less than 2% did so last year. CBS MoneyWatch reporter Irina Ivanova breaks down how to file your taxes without paying a cent. Source

Donald Trump on Tuesday will become the second impeached president to deliver a State of the Union address. Source

The first voting contest of 2020 Democratic primary campaign takes place today with the Iowa caucuses. The most recent polls show a tight race for the top spot. Source

Ukrainian leader cites air traffic control exchange as proof that Iran, “knew from the start that our plane was shot down.” Source

House managers and the president’s lawyers will have four hours to make their final arguments. Source