Do you think Columbo realized before he walked out of the office that the suture was put in his pocket? Perhaps he realized right when the Doctor bumped into him or some other time on the way to the office or before leaving, and he left and came back to string along the killer or to shock him.

I don’t know. Columbo looked pretty perplexed as he was leaving the office.

Dr Mayfield should have retrieved the suture from the coat that Columbo was wearing immediately, and put it in his pocket and then there would be no evidence left. then he could have discarded it at some later time. but not in his office. as soon as the door shut and Columbo was gone, he should have done just that. and then he would have been home free

He would have had to do it quick because Columbo came back right away. And if he did and if the coat was moved even slightly Columbo would have noticed and could have searched the doctor again