A common mistake that people make with any type of bug or insect is that to assume that the only way to kill it is by poisoning it. In other words, it doesn’t occur to most people that there are many options other than fly sprays for killing cockroaches, flies, mosquitoes, or spiders.
And these options should be considered, because as anyone that has used a fly spray will know, with modern formulas (containing synthetic pyrethroids) the insects go through a hyperactivity period before they die. This is because of the mechanism of the insecticide. Essentially, they lose control of their muscles and this causes them to shake themselves to bits, internally. This process can be very unpleasant as with a cockroach you see it scuttling uncontrollably all over the place.
There is, however, a better way. Use an oven cleaner. In particular, use Mr Muscle.
This product has a very rigid foam which drowns the cockroach and immobilise it while it essentially suffocates. So you simply spray it on, the cockroach gets immobilised in the foam, and then you come back a a few hours later and wipe it up