What is a word for "detaining without trial"?

I read this in a news about the passing away of a prominent political figure. One of the critics mentioned that during the time when he was in power he used to "detain without trial" his political oppositions to silence them.

In the news they used a single word for that phrase, but I can't remember it.

What is a word for "detaining without trial"?

I've tried to search for "detain without trial", "imprisonment without proper trial", "detaining without hearing", etc (without the quotes), but all I could find were internment, which is more about concentration camp, or remand, which is about the pre-trial detention. (I hope by putting what I searched for, future people who search for the same thing will find this page with the answer!)

The word I'm looking for seems to mean that the people never went through any trial at all, and so the prominent political figure _____ the political oppositions.

Solution 1:

The word I would use is internment (as identified in the question), which Wikipedia describes as

the imprisonment or confinement of people, commonly in large groups, without trial

though I would not see it as necessarily going as far as the extremely negative associations of concentration camps from World War II.

For individuals rather than groups, I might use detention, which I would almost never use for being held before a trial (instead using remand) or after a trial (instead using prison).

Solution 2:

Immure is a possibility:

verb

[WITH OBJECT]
Enclose or confine (someone) against their will:

The prominent political figure immured his political opponents.

Solution 3:

Impound includes imprisonment, and is not normally associated with the due process normally offered to people:

verb

[WITH OBJECT]
1.0 Seize and take legal custody of (something, especially a vehicle, goods, or documents) because of an infringement of a law:

2.0 Shut up (domestic animals) in a pound or enclosure:

2.1 Lock up (someone):

In situations where political prisoners are taken and help without due process, it is normally rationalized in a tyrannical legal framework:

The prominent political figure impounded his political opposition.