"indeed I know" is correct and can be used in written English.
You can use this phrase to express certainty or agreement. For example: Q: Do you know what time it is? A: Indeed I know - it's eleven o'clock.
Indeed, I know that this is happening, and I feel powerless to stop it".
Indeed, I know 17-year-olds who plan on trying to vote and some friends who say they will vote twice.
Indeed, I know it will soon become known, so I choose to release this brief notice that I am now filing for divorce".
SECOND MAN: I know it, I know it, I know it, I know it, I know it, indeed, indeed, I know it.
Indeed, I know of a number of law firms working for the miners who have done well out of the government compensation scheme without looking to the claimants for a penny.
Indeed, I know a few fellow dieters have gone through that phase (one in particular has been on Atkins for a few months and hasn't smiled once - but I'm willing to believe that he's just an unhappy person for other reasons right now).
I'd never known anyone who wrote; indeed, I knew few people who read".
Indeed, I knew one young man who became a lawyer just so that he could stand in the shoes of Atticus Finch, who seeks justice for Tom Robinson, a local black man accused of raping a white girl, Mayella Ewell.
"Obviously, I'm very pleased indeed as I know their families and service colleagues will be," said the British foreign minister, Jack Straw.
And indeed I already know of one (off-the-record, for the moment) partnership to stem from the event — just weeks or so after.
Indeed I do know people who are saving up for Hamilton instead of going to multiple cheaper options.
