Ijin is stupid here. He should've known the parent would try to call the one interrogating him and it was already implied that he's suspicious of that person too. The last he could do is to be the one to actually tell him to stay put and let him do the job.
It makes sense. But well, we are in a story where the obvious happens. The good-natured detective had his son run over and nothing much was done. This is common in most countries with corrupt police and justice systems, such as Brazil and the United States (I don't know if South Korea has as much corruption, but I know that the issue of social hierarchy disguises some corruption quite a bit).
The congressman who runs and runs (who reminds me of Gustavo Gayer in Brazil) tried to "put an end" to IJin while the ass-faced aide talked to his corrupt contacts in the police and the criminal underworld to clear the slate.
IJin wasn't such an idiot in the end. He acted like a good-natured mercenary would. Otherwise, he would have received a metal club to the back of the head...
In a corrupt system, sometimes what is right is "outside the law"...
