>> reporter: but what about a those reminders during the day? shouldn't one of those have triggered his mind to say, wait. cooper. where's cooper? >> i think that's a fair question to ask. if ross had forgotten that he had a son, seeing a picture of cooper would have reminded him that he had a son. he didn't forget he had a son. once ross slipped into his work day, he had every reason to believe that cooper was at the day care. >> reporter: as for those witnesses who said ross seemed detached, they didn't know him, the defense argued. so they called people who did, like his friend billy. >> in my opinion, he was just incredibly loving and doting. >> reporter: a colleague from home depot. >> when cooper was born it's all