Turkish has two suffixes that are used for past tense. You have already seen -Dİ, and in this lesson you will learn about -mİş.

In Turkish, we use -Dİ for things that we witnessed firsthand, or for things we are absolutely sure happened. We use -mİş for events that we have not witnessed ourselves, but heard from others. For example if one says:

Kamil dün kalp krizi geçirdi.

Kamil had a heart attack yesterday.

One would understand from this sentence that the speaker was present when the attack happened, that he saw it with his own eyes. However if one says:

Kamil dün kalp krizi geçirmiş.

(Apparently) Kamil had a heart attack yesterday.

One would understand from this sentence that the speaker heard about the attack from someone else. Even if we heard it from Kamil himself, we still use the -mİş form.

The suffix -mİş is also used when making inferences. For example, if you see your boss' jacket on the coathanger, you infer that he arrived in the office and you say:

Patron gelmiş.

(Apparently) the boss arrived.

To say Patron geldi would imply that you actually saw the boss coming in. This is the difference between -Dİ and -mİş.

Now, you may think "Wow, did you all really need a suffix for this differentiation? Like seriously?" But beware, this suffix is used a lot, and if you use -Dİ where you should use -mİş, people will find this strange. Unless you are a foreigner of course, since most people will understand your confusion. The suffix -mİş is especially useful when gossiping, which you of course never do.

When it is used combined with first person, it conveys the meaning that the speaker acted unknowingly, or did something so automatic that it was out of his/her consciousness. For example:

Bütün şişeyi içmişim.

I drank the whole bottle (apparently, without even realizing)

Here's the chart for the conjugation of evidential past.

Evidential Past Tense	Singular	Plural
First person	-mİşİm	-mİşİz
Second person	-mİşsİn	-mİşsİnİz
Third person	-mİş	-mİş(lEr)

Breakdown of Duydum ki istifa etmişsin.