George Zimmerman's brother, Robert Zimmerman Jr., apologized Wednesday night CNN's "Piers Morgan Live" for his controversial tweets comparing Trayvon Martin to an accused baby killer.

Robert Zimmerman called it "a mistake" to post the tweets, including one that included a side-by-side picture of Trayvon Martin and a 17-year-old suspect charged with killing a 1-year-old boy in Georgia. Both the Georgia teen and Martin appear to be giving the camera the middle finger.

The image included the caption: "A picture speaks a thousand words. Any questions?" and was included at the end of Zimmerman's tweet, which read:

"@NAACP @benshapiro @NRA Alleged FBpics of 13mo. old Antonio Santiago's alleged killer & #TrayvonMartin #uncanny pic."

Piers Morgan asked Robert Zimmerman about the controversial tweets Wednesday night.

"It seemed to me you were saying was: 'This is why young blacks are risky.' In other words, 'That was why my brother, George, did what he did to Trayvon Martin,'" Morgan said.

Robert Zimmerman replied: "That's certainly one way to read it, and that seems to be the way a lot of people have interpreted it. And I don't think twitter is the place to make points about what you recall a year ago, because the recollections that I have or that we have as a family specifically are very different than can what be portrayed in 140 characters. I realize that those were controversial and offensive, and I don't think that was the right thing to do that way."

"I realize those were controversial and offensive, and I did publicly apologize for them," Robert Zimmerman added. "I'm a human being. I'm being upfront about what I did. I made a mistake."

He went on to admit that, ultimately, his rant on Twitter may not have helped his brother, George Zimmerman, who faces a second-degree murder trial set for June in Sanford the shooting death of Trayvon Martin in February 2012.

Robert Zimmerman said he was trying to make a large point in his tweets about the media's portrayal of Trayvon Martin and George Zimmerman.

"We've been led to believe that it's a junior-high-school-aged person because of the pictures," he said, referring to early photos released of a young-looking Trayvon Martin that were actually taken years before the shooting.

Robert Zimmerman has since deleted the tweet that included the picture.

Information from CNN was used in this report.