The suspect, Cesar Sayoc, has publicly supported Trump. He was arrested in connection to a series of mail bombs addressed to former President Barack Obama, former Secretary of State Hillary Clinton, and others.
"He was insane a long time before. You look at his medical records, he was insane for a long time," Trump said in a Fox News interview released Monday, apparently seeking to distance his political movement from Sayoc.
More than a dozen explosive devices were intercepted by postal services and law enforcement officials earlier this month. The discovered bombs came in the same month that a gunman carrying multiple weapons entered a Pittsburgh synagogue and opened fire, killing 11 people and injuring six others.
The president previously claimed, following both the explosive device discoveries and the shooting, that "Fake News" has caused "great anger" in the country.
— CNBC's Kevin Breuninger contributed to this report.