George Tschaggeny, 51, was arrested at a homeless encampment under an overpass after a tip from an employee of a Domino's Pizza restaurant in the area, Portland Police Bureau officials said at a Friday press conference.
Police had released surveillance footage on Thursday of a man carrying Best's backpack leaving the Portland MAX commuter train shortly after the stabbings.
Tschaggeny was found wearing Best's ring, which he apparently had removed from Best's finger after the stabbing, said police spokesman Pete Simpson.
Police also recovered the backpack but Best's wallet was missing, Simpson said, adding that his family had hoped to recover phone numbers Best carried in the wallet.
Tschaggeny will be charged with theft, evidence tampering and abuse of a corpse, Simpson said.
Best, Taliesin Myrddin Namkai-Meche and Micah Fletcher were stabbed on May 26 when they intervened to prevent Jeremy Joseph Christian, 35, from harassing two young women who appeared to be Muslim by shouting ethnic and religious slurs. Best and Namkai-Meche died of their wounds.
Christian was arraigned on Tuesday on three felony murder charges, one felony assault charge, three felony weapons charges and two misdemeanor counts of intimidation.
In court on Tuesday, Christian shouted, "Death to the enemies of America ... You call it terrorism. I call it patriotism.”
Federal Bureau of Investigation spokeswoman Beth Anne Steele said earlier this week that the bureau is investigating the attack to determine whether to charge Christian with terrorism or a federal hate crime.
Immediately after the attack, the Council on American-Islamic Relations called on President Donald Trump to condemn violence against Muslims.
In a Monday tweet, Trump called the attack "unacceptable," and commended the stabbing victims for "standing up to hate and intolerance."
According to The Oregonian, a witness to the stabbings said Namkai-Meche’s last words before being taken away by paramedics were, “Tell everyone on this train I love them."