you can't let your personal emotions get involved. >> reporter: yeah. >> you can't allow tunnel vision to take over. your job is to investigate. look at the evidence and then go where the evidence leads you. >> reporter: detectives were still canvassing fellow students, and teachers, school administrators. anybody who could help them nail down nathan's movements on thursday morning, the time of the murder. and again, if anybody knew, it would be daniel. who, after all, watched over nathan, drove him around, looked after him. but it turned out nathan was at home in suburban dallas the night before the murder. his mother drove him to school that thursday morning. he said he was doing homework in a computer lab at the time of the murder. but was he? >> and he was in school from what time to what time? >> i don't know. >> what time did you pick him up thursday? >> i picked hip up around 10:00. >> reporter: detective ellzey also asked daniel what he was