What in god's name does an out of control killer's news cycle have to do with interviewing a Presidential candidate' former acquaintances?
Well, it had been routine for news outlets to explore a candidate's past to find out the "real people" that could vouch for the person a said candidate claimed to be. See: Romney being a bully in high school and mistreating the family dog.
Remember the Bush stories about draft dodging, cocaine use, DWIs, his wife getting away with vehicular homicide and being an an insider country clubber? Not to mention McCain's blowing up an aircraft carrier, submitting to Vietcong torturers and marrying up in class to own 8 houses?
It wasn't until Obama came along that asking questions about a guy who grew up outside the USA, attending elite schools, seeking out radicals and espousing flaws and fundamental transformations of our constitution became "extremism".