The intelligence target is not randomly selected but it is decided through the formal organizational process of the agency in advance. At least, there are lists of the monitored and the formal assets, which are budgeted by the government, not different from any other administrative entity.
The subject is not always acquired as an asset successfully. If absolutely necessary to obtain the target, the spy conducts a torture beyond just a manipulative operation. Especially if you have no protection from the government or you become one of the main targets of your own government, you are assumed to be an easy target of the abuse.
The torture has been a common practice of the spy for a long time, which is basically effective, but it is not so sure that you will get a right intel from this conduct. The subject is highly likely to tell a lie for an avoidance of the harsh assault, which is basically along with what the spy wants to have.
The spy can create an intel as they want from the torture, but not necessarily to obtain the truth. Moreover, there is no way to tell whether the intel is correct or not, just by the torture, hence it is nearly worthless to obtain a secret information. It is just useful for the spy to continue their operation as they can create a necessary information from the abuse.
This paradox should also appear at the assetization. Even if the spy acquires the target as an asset after the torture, this individual is not necessarily loyal to the intelligence organization. It might be ended up with hiring a potential enemy inside their network, nevertheless, they have employed a torture.
The general image of torture is more or less punching and kicking, or maybe progressed to break a finger or burn with a red-hot iron. There have been many methodologies created through the human history, but the majority of them are categorized as an illegal under the modern rule of law.
When employing these physical methodologies, it should create a big problem later on if the subject has survived. If that is the case, it is better to kill the target, rather than just torturing.
Furthermore, the traditional torture can be availed when confining a target under their custody, but it is difficult under the other circumstances.
The most fundamental torture is a deprivation of the sleep, employed by the intelligence organization, which can be used for the most of the occasions. It does not require a physical contact, hence it is the most available without any proofs of their illegal conducts.
As a matter of fact, you become sleepless even with a slight noise. When your sympathetic nervous system is dominant, you cannot sleep, which does not require a huge operation, just irritating your nerve.
Even if you fall asleep, you can be waken up every time under the REM sleep. Its state is easily monitored by the brainwave, whose technology is cheaply purchased nowadays. You should wake up when noised under this brain state.
This is kind of an extension of the electromagnetic wave operation, as those share the same brainwave technology. Moreover, this operation is conducted just by the wave, not requiring a physical noise.