To whom it may concern,

Pat Snow is to be considered a person of interest. They were seen speaking with Jane Doe at the corner of 31st and Main last Tuesday. 
This is relevant to the other thing and so should be followed up on. Don't let Jack Smith know that you know that we know that they know the thing.

Regards,
Joan Vi
Director of Communications
jvi@email.com
(312) 555-0123