Question: Is there scientific evidence that the consciousness might still be in the body after breathing ends?
Answer: It is actually the other way round – science has been unable to prove that the consciousness leaves the body right after breathing ends. There is no direct relation between the functioning of breathing with the functioning of the consciousness. Why is this said?
There are occasional cases, of those medically (and thus officially) pronounced ‘dead’, who nevertheless revive later. This is proof that the consciousness still existed and operated through the body, despite being scientifically thought to be ‘gone’.
Here is a recent example, as reported on 25 August 2020 in the United States, of someone who was about to be embalmed, who revived in time: https://www.nytimes.com/2020/08/25/us/michigan-woman-alive-funeral-home.html.
To prove that the above is not an accidental or ‘freak case’, but a recurring international phenomenon, here is another case, in Poland, as reported on 14 November 2014, of someone who revived in the mortuary, also after being certified dead: https://www.bbc.com/news/world-europe-30048087.
These cases also prove the limits of current science for understanding and measuring the workings of the consciousness. With such cases still occurring very recently, they further prove how science is still not as advanced as imagined, even in this day and age. There could be many other undetected and thus unreported cases. That said, not reviving after ‘death’ does not mean the consciousness has already departed.
In Buddhist practice, that there are changes in the expression and complexion of the deceased during support-chanting, from looking disturbed, rigid and deathly grey, to looking incredibly peaceful, supple and rosy, is proof enough, that the consciousness was still attached to the body, thus effecting changes through it. The final expression and complexion after ample offering of guidance and support-chanting is so incredible that the deceased often looks as if still alive and in their prime, sleeping peacefully. This is very common.
Only three kinds of people have their consciousness depart from their bodies very swiftly –  those with very proficient spiritual practice, who depart for Pure Land (or liberation) immediately,  those with very positive karma, who depart for a higher realm immediately, and  those with very negative karma, who depart for a lower realm immediately. For average people, due to habitual attachment to what is most familiar – their bodies, their consciousnesses usually linger within for some time – till karma forces them to leave, or till there is guidance on where best to go.
This is why, in Buddhist practice, touching and moving of the deceased is abstained from as much as possible, to prevent potentially disturbing the consciousness, that might still be within. What more, there will be magnified sensitivity by up to nine times. As embalmment and application of make-up is ‘ultimate’ touching and moving of the body, both inside and outside, it should be abstained from. Crying in the presence of the body should also be abstained from, to avoid provoking attachment or aversion of the deceased.
A common concern is that if there is no embalmment done, there might be decomposition of the body during the wake. However, the number of cases heard, of smelling any possible decomposition from professionally sealed airtight caskets is exactly zero (e.g. in the context of humid Singapore, despite wakes of 3 to 7 days). Bodies without embalmment will not be viewable once sealed. As such, embalmment is primarily for family members to see the bodies. For those who cannot arrive on time, pictures and videos can be taken before sealing the casket.
The Three Great Essentials When Approaching The End Of Life