( CNN ) -- Robert Zimmerman Jr. , the brother of the man who shot and killed 17-year-old Trayvon Martin , apologized for his controversial and offensive tweets . In one , Zimmerman juxtaposed a photograph of Martin with one of 17-year-old De'Marquise Elkins , one of two teenagers charged with killing a baby in Georgia . Both Elkins and Martin appear to be flipping off the camera . `` A picture speaks a thousand words . Any questions ? '' the tweet reads . In another tweet , Zimmerman writes : `` Lib media shld ask if what these2 black teens did 2 a woman & baby is the reason ppl think blacks mightB risky . '' Speaking on CNN 's Piers Morgan Live on Wednesday night , he apologized for the messages , saying they were n't the `` right thing to do . '' `` I realize those were controversial and offensive and I did publicly apologize for them , '' he said . `` I 'm a human being . I 'm being upfront about what I did . I made a mistake ... Unfortunately ( it ) may not have helped George . '' 5 things to know about the case . His brother , George Zimmerman , has been charged with second-degree murder . Zimmerman acknowledged shooting Martin but said it was in self-defense . Attorneys for Martin 's family have accused Zimmerman of racially profiling Martin and shooting him `` in cold blood . '' Robert Zimmerman Jr. said he was trying to make a larger point in his tweets about the `` media and their honesty in portraying the person who encountered my brother February 26 , 2012. Letters to Zimmerman show split opinions . `` We 've been led to believe that it 's a junior-high-school-aged person because of the pictures , '' he said , referring to Martin . `` The analogy is these are two people who chose to represent themselves in this way . One was accused of killing a baby , and whatever 's in his social media makes the rounds immediately ... However , the other person who almost killed my brother had he disarmed him -- my brother had every indication to believe he would have killed him -- his social media is off limits . '' Chief witness in Martin case lied under oath . Zimmerman 's tweets prompted a response from his brother 's defense team . Attorney Mark O'Mara told CNN 's `` Starting Point '' Thursday morning that Robert Zimmerman does n't represent his brother or his defense . `` Having said that , I 'm not sure where ( Robert 's ) heart was , but I 've always said for the past year that we have to have a conversation about race , and the Zimmerman case has brought it to the forefront , particularly the way young black males are treated in the system , '' O'Mara said . `` These type of tweets ... were insensitive to that , and quite honestly are the opposite of what I hope the conversation would be to try and figure out what 's wrong with the system and maybe a good way to fix it . '' O'Mara said he worries about how Robert Zimmerman 's tweets will affect George 's case . `` Everything that happens in this case is , if not overblown , hyper-focused upon , so that everything that George says or does is important , '' O'Mara said `` ... And certainly when a family member of my client says something that comes across as totally insensitive -- if not much , much worse -- ( it ) has an effect , and now we have to deal with it . '' Opinion : Trayvon Martin did not die in vain .
`` I 'm a human being ... I made a mistake , '' says Robert Zimmerman Jr . He tweets side-by-side images of Trayvon Martin and De'Marquise Elkins . Elkins is accused of killing a baby in his stroller in Georgia . Zimmerman says he was trying to make a larger point about the media .