You need a graduated system of interviewing. Start with quick-screening questions online, then a phone interview, then more in-depth online testing (nothing to

You need a graduated system of interviewing. Start with quick-screening questions online, then a phone interview, then more in-depth online testing (nothing too burdensome on the candidate, say an hour's worth), then several hours of interviews (perhaps all on one day) by various interviewers. You should also gather candidate's expectations/requirements in compensation, corporate culture, etc as early in the process as possible, to avoid disappointment. At any point in the process you should be willing to stop, politely but decisively, whether for jerkiness or for technical incompetence.