Richardson's remarks echoed those of Terri Chung, sister of Korean-American Kenneth Bae, who's been held in North Korea for more than a year. Chung said Tuesday she also was upset because Rodman, who angrily defended his trip to Pyongyang for an exhibition basketball game with other former NBA stars against a North Korean team, wasn't inclined to use his friendship with North Korean leader Kim Jung Un to discuss her brother's situation, CNN reported.
"He was in a position to do some good and to help advocate for Kenneth," Chung said. "He refused to do so. But then instead he has chosen to hurl these outrageous accusations against Kenneth. He clearly doesn't know anything about Kenneth, about his case. And so we were appalled by that."
Richardson, speaking on CNN Wednesday, said Rodman's conduct -- both in defending Kim and abandoning a fellow American who's been sentenced to 15 years in a brutal North Korean labor camp, is inexcusable.
"I think what's most reprehensible is his implication that Kenneth Bae, an American detainee on very spurious charges, who deserves to come home might be guilty," Richardson, a former governor of New Mexico, said on CNN's "New Day."
China's state-run Xinhua News Agency reported Rodman celebrated Kim's birthday Wednesday by singing "Happy Birthday" before the exhibition game. He also said he could feel the love North Koreans have for their leader, who is thought to be 31 years old.
Bae was sentenced to 15 years in a labor camp by North Korea last year on charges he intended to topple the government through religious activities.
During an interview with CNN Monday, Rodman suggested Bae did something wrong but did not specify what.
"Do you understand what he did in this country?" Rodman asked during the interview. "Why is he held captive here in this country, why?"
Chung said Bae, a missionary, was in North Korea legally as a tour operator when he was arrested in November 2012.
"This isn't some game. This is about a person's life," she said.
Rodman struck up a friendship with Kim in February, during his first trip to North Korea with a team of Harlem Globetrotters for an exhibition game attended by Kim, a basketball fan.
Rodman's latest trip to the reclusive country is just weeks after North Korea announced the purge and execution of leader Kim's once-powerful uncle, Jang Song Thaek.