THE FOLLOWING ARTICLE APPEARED IN THE

MARCH 1999 ISSUE

THE POISON SLEUTHS

DEATH BY DIESEL FUMES

-Dr. Anil Aggrawal

"Good morning doctor. Oh, my God, what are you doing today? You have the dead body of a old man today. What has happened to him? Please tell me."

"Good morning Tarun. The name of this old man is Shyam. He was a big industrialist and was about 83 years old. His dead body was found today morning at about 9 am in his Ford saloon car. This car was parked in his garage. I may tell you that this car was fitted with a diesel engine."

"So how do you think he has died?"

"That is what I have to find out. But police has a suspect with them, and they think that he has killed Shyam. Well, let me begin from the beginning. Shyam had a business associate Sohan Lal. Both Sohan and Shyam had been working together for quite some time. However lately they had fallen out over some monetary matter. Sohan is a relatively young man - only about 48 years old. The police has interrogated many persons who knew both of them, and all of them have told the police that Sohan did not have good relations with Shyam. The things had deteriorated to such an extent that on one occasion, Sohan had even threatened Shyam with dire consequences."

"Oh, I see. It does appear that Sohan has a hand in Shyam's killing."

"Shyam Lal lives alone in his big mansion. His wife died about two years back and his only son is settled in Netherlands. He comes to India only occasionally. Rarely a guest comes to his house to spend a night with him. So for all practical purposes Shyam Lal lives alone in his house. Shyam Lal used to remain quite depressed after his wife's death, and it appears he had lost all will to live, especially as his only son had also left him. Two days before, i.e. on Saturday evening Sohan invited Shyam Lal for dinner. He came to Shyam Lal's house in his own car, parked it at his house and from there both of them drove to a 5-star hotel in Shyam Lal's car. It was somewhat surprising to Shyam, but he thought that probably Sohan wanted to settle matters with him, and so accepted his invitation. They had their dinner and returned quite late - at about 12 midnight. We know these details because the police has made thorough inquiries from the hotel staff. Shyam Lal was not seen on whole of Sunday, and on Monday morning, i.e. today his dead body has been found in the garage in his car. So the presumption is that Shyam Lal died just after his return from the hotel. I have made some preliminary examination of the dead body, and from the various changes seen in the body, I am also of the view that Shyam Lal died somewhere around 1 am on Sunday morning, i.e. just about one hour after return from the hotel."

"So what do you conclude from all this?"

"Well, the police has come up with an interesting story. According to them, Sohan mixed some poison in his food surreptitiously when they were having dinner together. He came with Shyam Lal back to his house. There he left him, collected his own car from his residence, and drove away. Shyam Lal was already feeling weak from the effect of the poison Sohan had given him. He wanted to get some rest. But just as we was parking his car in his garage, he fainted and dropped dead within his car. His body was only discovered today."

"So what are they waiting for? They must immediately arrest Sohan."

"They have already done that. But Sohan is swearing he didn't mix any poison in Shyam's food. He says that he did want to patch up things with Shyam, and for this purpose he had invited him for dinner. But from the talks it appeared to him that Shyam was reluctant to his proposal. They had talks for about 2 hours after which Sohan came back to Shyam's house, bade him good bye and went to his own house. He does not know what happened to Shyam Lal after that. However the police are reluctant to believe his version. They are holding him, and interrogating him more severely, so he could come out with the truth."

"What do you think doctor?"

"Tarun, a forensic pathologist goes only by the evidence that he has with him. I am a forensic pathologist and I won't form any theories merely from the details of circumstances. From the circumstances, it does appear that Sohan has a hand in the death, but I would make my deductions only from the hard scientific facts that I have seen for myself. I went to Shyam's house and made some preliminary observations. The first thing that struck me when I was examining the car was that, a hose pipe was connected to the interior of the car from the exhaust..."

"Sorry to interrupt you doctor, but how is this observation important?"

"Tarun. It is a common method of committing suicide. Carbon monoxide is known to emit from all car exhausts. Many persons - especially in the western countries- close themselves in a garage along with their car, run the engine of the car and simply wait there till the level of carbon monoxide rises enough to kill them. The attraction of this method among suicides is that it is a very painless death, and all persons wanting to commit suicide want a painless death. A hosepipe going to the interior of the car from the exhaust means an arrangement had been made to let the carbon monoxide come inside the car."

"But doctor, these days most cars are fitted with catalytic converters. I believe such an advanced car as the Ford saloon, in which Shyam Lal's body was found must definitely be fitted with a catalytic converter."

"You are right Tarun. Catalytic converters convert carbon monoxide to relatively non-toxic carbon dioxide. This has not only enabled the carbon monoxide levels in the atmosphere to go down, but also reduced the risk of suicides substantially. Now anyone who makes this arrangement for the purpose of committing suicide is likely to fail. The reason is that carbon dioxide is not as deadly as carbon monoxide. In fact, if you read medical literature, you will find many instances of failed suicides because of these catalytic converters."

"Oh, I see."

"Tarun, with the coming of new vehicles on the Indian roads, there is now an apparent progressive increase in diesel-driven motor vehicles in all forms of road transportation. Diesel is a commonly used vehicle now and it is believed to be safer than petrol as diesel fumes contain substantially less carbon monoxide. However their emissions are still potentially toxic. Diesel engines emit more than twice the amount of sulphur dioxide than that contained in petrol emissions. They also emit 14 times the amount of black smoke, i.e. particulate materials, than of petrol engines. Diesel emissions also contain marginally more nitrogen dioxide than petrol. Petrol, as I told you earlier, however creates more carbon monoxide - 28 times to be exact- than diesel."

"Oh, I see. So if someone wants to commit suicide in the manner you just described, probably he is better off with a petrol engine than with diesel engine?"

"You are right Tarun. The reason is obvious. Petrol engines create substantially more carbon monoxide. Of course only those petrol engines would do so, which are not fitted with catalytic converters. I must however tell you that both fuels cause acute toxicity if substantial quantities of their emissions are inhaled. However the mode of toxicity would be different. Whereas petrol engines cause death by carbon-monoxide poisoning, diesel fumes cause death by blocking the air passages with soot and other material in the emissions. The absorption of toxic materials in the latter case is increased owing to the blockage of tiny lung alveoli by the soot particles. These soot particles effectively plug the alveoli, thus "holding back" the toxic fumes within the alveoli. This greatly enhances the absorption of toxic substances. Thus although diesel fumes do not contain much carbon monoxide, they can still be very harmful."

"Doctor, have you found any evidence that Shyam Lal died of diesel fumes?"

"Tarun when I examined Shyam's heart, I found that the coronary arteries - the arteries that supply the muscles of the heart - were blocked to a great extent. However the amount of blocking was not sufficient to cause death, so I looked at other organs for more clues. The interesting finding was that the windpipe (trachea) and the bronchi were thickly covered with soot. The lungs were very much congested, which meant that they had been exposed to some irritating substance like diesel fumes. But what clinched the diagnosis in favour of death by diesel fumes was the fact that there were thick beads of black oily sticky material in the smaller bronchi. When I cut the lungs and pressed the cut ends, these thick beads of oily materials could be expressed. These beads were nothing but toxic material -including some diesel fuel- in the lungs. To see if the blood had any carbon monoxide in it, I did a toxicological analysis of the blood too, and found that there was less than 5% saturation with carbon monoxide. This indicates that there wasn't a substantial amount of carbon monoxide in the fumes that Shyam Lal inhaled. It is almost sure that Shyam Lal died of diesel fumes."

"Oh, that is interesting. So would you reconstruct the events for me doctor?"

"Sure. On Saturday evening, the talks between Shyam Lal and Sohan failed and this sent Shyam Lal again into a bout of depression, which he was already suffering from. He came back to his house and probably decided to take his own life. He had already lived a full life, his wife was no more there and his son was living far away from him. On that day, probably he lost all will to live. He was an educated man. He had read about deaths by carbon monoxide. I personally feel that he intended death by carbon monoxide. But it was a diesel engine, which does not emit carbon monoxide. He ultimately died of diesel fumes. Come let us tell the police that Sohan is innocent and they should release him."

"Very clever indeed. This was a most interesting discussion doctor. Without your masterly deduction, police could have unnecessarily went on harassing Sohan. People might have thought, it was a case of killing by Sohan. Tell me what are you going to tell me the next time?"

"Tarun, next time, I would tell you about death by arsine gas. "