Brain teaser

Here goes, try solving this ;)

A robbery occurred at a bank in a prestigious neighborhood
late one night. After a thorough investigation the police
came up with a suspect and went to question him on March 26.
However, when they asked the man where he had been on the
28th of the previous month he said his mother had died and
he was out of town making funeral arrangements and attending
her funeral. He said he left on the 27th and returned on the
30th so he couldn't possibly have committed the robbery. How
did the police officer know he was lying?

(answer further below)














The police visited him in March, so the previous month was
February. Since February only has 28 or 29 days he couldn't
possibly have returned on the 30th.

I can't believe I didn't see that! Did you?