Should Criminals who are on a death/execution role be donated to scientific purposes?

In some countries executions still occur. Many prisoners are on death row for their crimes. Some may say that this is inhumane and cruel and should be banned in all countries. However there are still places that carry out the death penalty. This may be to prevent the specific criminal from reoffending or as a deterrent to others. It might also be to make the victim's family feel safe or to satisfy them that the criminal has been punished. Alternatively, there are also people who believe that this contravenes basic human rights and that the whole idea of the death penalty is wrong as there are too many cases where there have been mistakes and an innocent person has been on death row.
I however agree to the idea of criminals being donated to science research as there are more benefits from it than just killing them with only one benefit coming from it - never coming back to kill again, is the only benefit from executing them. What are the benefits of donating criminals to science? , apparently there are many, for example if a new born virus or bacteria has been found or even worst the virus merging with other flu viruses. For example infected bird, pig and bat, if one of the flu from one of those species has merged with a human version (flu) i.e. bird flu meets a human flu- it is very easy for a new virus to begin, taking bits of both flu version to evolve. The bird flu can only transmit the deceises to human (through close contact with infected birds) and other birds, but not human to human anyhow scientists has found out that in order for deciese to be carry on from human to human it acquire three stage of mutation which for example are bats or the swain flu therefore testing on animal might make it worse than beforehand. And who might know what new born virus is going to be found in the future it might be one of the worst viruses in the history and testing a deadly flu on animals might mutate the virus even further to a deadlier virus. So what choice is left? Human apparently would be the second choice and by donating criminals would be an ideal choice for less mutation to happen inside the host body. other benefits of criminal being donated are to overcome crowed jails. As I have heard that many jail are overcrowded with inmates which prisoners has to share a single cells, while some other prisoner doesn’t have an in-cell toilet and donating criminals who are on a death role would slowly overcome this problem. These criminals would help medical research to bloom. Using animals would work although it takes years and years whereas using the accurate subject would make the process faster also to prevent animals from extinction. Dead bodies can also still be a value by donation to science for organ donations for people in need or donate dead bodies to body farm research facility where dead bodies can be studied for a better understanding of decomposition process. This will help the investigator to have greater knowledge of understanding and able to identify by telling from the body decaying process of how many days the victim was dead - it would be a great value for them and the body farm science research facility.
On the contrary there are many other people who believe in human rights and