The other uses of “dürften” and “sollen” outside allowed to and shall/ought to

Question

I understand what the modal verbs "sollen and "dürfen" mean in regards to "shall/ought to" and "is allowed to" respectively. But how do these verbs function in regards to these following sentences?

I usually read such usage in newspapers or websites so I'm guessing it must be a more formal method of stating something but it's usage just seems strange (to my current level of german). And if it were to be a more formal way of saying things, would this be actually used in everyday casual speech or just the newspapers?

"Elitesoldat soll Top-Terroristen vor drei Jahren getötet haben"

That sounds very odd to me - it seems like the paper is ordering the soldier to kill, like they're saying the soldier shall have the terrorist killed.

"X soll Y ermordet haben."

So the pattern so far seems to be that they tend to be used about bad stuff..

"Dabei dürfte etwas schief gegangen sein, denn es kam zur Detonation"

That sounds to me like they said that something awful was allowed to happen because then it detonated but I'm sure I'm missing the actual meaning.

Answer 1

It is possible to construct the Perfekt of modal verbs in two ways:

Er hat einen Terroristen töten sollen.

The auxiliary is finite and sollen not. It is very uncommon to say it like that in Standard German, usually you would say:

Er sollte einen Terroristen töten (Präteritum)

Both means that in the past someone was tasked to kill a terrorist.

The alternative is - and you know it from must have - is to use the modal as auxiliary and put the auxiliary of Perfekt into Infinitive and use Partizip Perfekt of the main Verb:

Er soll einen Terroristen getötet haben.

This means that it is said, assumed, thought that he has killed a terrorist.

Now the example with dürfte is the same, only that dürfen is Konjunktiv II:

Dabei dürfte etwas schief gegangen sein, denn es kam zur Detonation.

dürfte assumption based on „reason to have to believe“. „must“ would be more fitting here, as it is evident that something went wrong. It is more cautious, though. A more fitting example is:

Er ist noch nicht da, er dürfte im Stau stehen.

Here a good guess is made about the most likely reason for someone being late.

German modals are quite flexible and versatile. sollen is the worst:

Er soll trinken.

Either you mean that he should drink, or that you assume that he drinks as a habit. If you put that into Perfect with modal auxiliary, only the latter reading is plausible.

Answer 2

Words like "müssen", "sollen" or "dürfen" have in common that they express some uncertainity.

Peter sollte Milch kaufen.

Peter should buy milk, but it's not shure if he really will do it.

Regula darf den Kuchen essen.

Regula may eat the cake, but will she do it?

If you use these words in the past form, you express your uncertainity whether someone (or something) is really responsible for something that has happened.

Wer hat den Kuchen gegessen? Das dürfte Regula gewesen sein.

Who has eaten the cake? Because I know that Regula was allowed to eat the cake, I assume that she has really eaten it - but i'm not sure.

Someone told me that Markus has stolen a car. I haven't seen it with my own eyes and can not be sure about the story. Now I tell you about it.

Markus soll ein Auto gestohlen haben.

This way to express your uncertainty about past events is not reserved for bad things. However, if you are telling something bad about a persons and you are not really, really sure, you should absolutely use this form.