Finding login or user name of last person to use a DB

Question

The boss has asked for a list of DB names along with size and name of last person to use that DB. I've found resources for when a DB was last accessed but for by whom. How would I solve this?

SQL2008R2 being used and so far I have this:

exec sp_MSForEachDB '
use ?
select ''?'', (SUM(df.size)*8)/1024 as ''Size (MB)''
from sys.database_files as df
'

It is acceptable for the last person aspect of the answer to be fuzzy or loose. i.e. as long as it's someone who went near it sometime vaguely recently that is "OK".