Protesters hang up a flag which reads, "Racism lives here", above a depiction of St. Louis, Missouri, outside the City of Ferguson Police Department and Municipal Court in Ferguson Missouri, March 11, 2015. [Photo/Agencies]

WASHINGTON - US President Barack Obama said in an interview aired on Monday that racism was still embedded in the United States.

"The legacy of slavery, Jim Crow, discrimination in almost every institution of our lives, you know, that casts a long shadow, and that's still part of our DNA that's passed on," Obama said in an interview with comedian Marc Maron for his popular podcast "WTF. "

"We're not cured of it," added Obama. 'Societies don't overnight completely erase everything that happened two to 300 years prior."

Obama's sharp remarks about ingrained racism in the United States came less than one week after a white gunman shot dead nine black churchgoers at the Emanuel African Methodist Episcopal Church, one of the most prominent black churches in the United States, in Charleston, South Carolina.

Dylann Roof, a 21-year-old white man, was arrested on Thursday and charged with nine counts of murder for the massacre at the black church.

Meanwhile, a website surfaced on Saturday with a racist manifesto purportedly written by Roof, explaining why he allegedly targeted the Charleston black church. Employing defamatory words, the 2,444-word manifesto was fraught with a racist ideology of white supremacy that once detailed the writer's approval of segregation and slavery.

Calling African-Americans "subconsciously viewed" by the whites as "lower beings", the manifesto called segregation a "defensive measure" against the African-Americans.

"Not only did it protect us from having to interact with them, and from being physically harmed by them, but it protected us from being brought down to their level," said the manifesto.

The US Federal Bureau of Investigation is currently investigating who was the author of the manifesto. According to the US TV network NBC News, the website was registered under the name Dylann Roof, using Roof's mother's home address.