The main spy operation is assumed to obtain an intel, but it also means to spread it on the other hand. They have circulated an information favorable to their own country or a fake to disturb a situation in the targeted country. These two intelligence operations share the same route, in or out, though this network is not necessarily availed just for the information exchange.
Fundamentally, the spy acquires the target as an asset. It is not always successful, which sometimes requires a tremendous time to hire, while they render the subject harmless if failed.
It is quite often to eliminate the target socially or physically. For example, the spy instigates the subject to commit a crime as an operation, resulted in either to become an asset or to be jailed, if succeeded.
In this case, the intelligence is indifferent to either of the choices, as they cannot control an outcome of the accident fully. There should be a preference, but they can contain the subject as an asset or complete an elimination once sent to the prison.
Although as said, it is not always successful. If it is failed eventually, they might pursue just an eradication when giving up an assetization. The physical elimination just means an assassination, which is a common practice, though it is quite limited to kill their subject opaquely in the modern world.
For example, the spy often uses a methodology to eliminate a target by a traffic accident, whose knowledge has been accumulated through the past experiences. Their technique is quite intricate, which perfectly looks like a real accident.
Having said that, it is basically framed hence there is a possibility to find a trace when looking back a process how to reach the accident. Furthermore, this attempt is not necessarily successful as well, especially when you realize and prepare for a traffic accident plotted by the spy.
The spy can sicken a subject. You are going to fall ill when taking a dangerous drug or poison. I have experienced both of them for many times, but I could not confirm perfectly where I got those. As you can imagine, the symptoms always appeared shortly afterward and I traced my action and behavior, though it has been always difficult to narrow down the possibilities to the single.
When the specific chemical substance enters into your body system, it is easily found out, later on, hence the cause can be revealed more likely than that of the car accident.
There is another common methodology to drive a target to commit a suicide, which is extended to fake the murder as a suicide, both of which are well planned not to reveal as an assassination. Although, these are also not perfect, hence they might kill the subject opaquely if really necessary to eliminate.
These operations require more time and money to prepare, with many intelligence assets to hide its true nature. When availing many people to be assigned to each small piece of the whole orchestration, it is hard for all of them to realize what really is going on. In this process, they can utilize ordinary people, therefore the intelligence organization hires them if worthwhile for the operation.