"Back-Room Boys” Who Help Catch Criminals

Press, Volume CIV, Issue 30811, 24 July 1965, Page 5

"Back-Room Boys” Who Help Catch Criminals

(Specially written for "The Press” by

GARRY ARTHUR)

it murder? Was the suspect at the scene of the crime? Did his knife inflict the fatal wound? These are the sort of questions to which the police seek answers in a small laboratory at the top of the Government Buildings in Worcester street.

It is to the microscopes, spectroscopes and test-tubes of the Christchurch district laboratory of the Chemistry Division of the Department of Scientific and Industrial Research that the police turn for scientific evidence that will help find a criminal and prove his guilt.

For the detective hot on the scent, speed is the vital factor, and that is one of the reasons for the existence of district laboratories, working in close conjunction with the division’s main laboratory in Wellington. This is particularly so in, a poisoning case. The sooner ‘ toxicological speciems can be got to the laboratory the better, and the sooner the poison is indentified, the sooner its source can be tracked down. The poison cantharadin is one which the Christchurch laboratory has indentified for the police. In a poisoning case in 1963 the laboratory was able to show that the sample found by the police was the same as that stocked by a chemical supply firm where the suspect worked, but different from samples from two other sources. An infra-red spectrophotometer was used on the cantharadin samples to show that the one used in the crime was consistent with one source only. The chemists have even been able to show that sand in the shoes of a woman attacked at Spencerville was the same as that in one particular spot, but different 1 from sand samples taken i from other spots nearby. j

Stolen lead ingots were taken to Wellington for spectrographic tests to determine what elements were in them, and in what quantities. Chemists were able to say that the stolen lead came from a particular batch. Burglars operating in Christchurch might watch j their steps more closely if they knew that the laboratory can go so far as to show that the dust, sand and dirt •found on their footwear can j be compared scientifically with footprints found on a windowsill. The chemists can also match the prints to the shoes, identify explosive stains, match up glass and paint fragments, analyse ink stains, and identify hairs and fibres. Vegetable matter to be analysed for police purposes is usually sent to the Botany Division of the D.S.I.R. Sophisticated machines help the Christchurch analysts in their work. The constituents of a volatile substance can be determined by injecting a sample into the gas stream of a gas chromatograph. Spectrophotometers working in visible light and ultraviolet light identify barbiturates and other drugs in toxicological work, sorting out two drugs in one sample. Ultra-violet light has also been used to trap "tillticklers.” When a man was suspected of robbing a firm’s i cash register, fluorescent ! powder was sprinkled on the i coins, and the hands of those iwith access to the till were

later subjected to ultraviolet light. The glow from the suspect’s fingers showed that he had handled the coins.

After a tragic fire in which a man and four children died at Avonhead, laboratory tests showed that petrol had previously been poured in practically every room, discounting speculation that explosives may have been used. Analytical tests have also been invaluable in tracking down hit and run drivers, once determining from a single flake of paint that the missing car had had nine separate coats of paint of specified colours. Safebreakers have been caught too after the chemists detected gelignite blast traces on banknotes found in their possession.

A very real advantage to the police in having a district laboratory, says Mr N. P. Alcorn, the district analyst, is that detectives can come to the laboratory and discuss the work with the chemist on the job. Forensic chemistry is not the only job of the district laboratory of the Chemistry Division. It has a regular programme of public health tests, analysing foods, drugs and water for the Department of Health, and makes regular tests of the gas supplies in the city and provincial towns. The local milk supply is tested regularly, and water supplies are examined and investigated for mineral land other constituents. ■ Research is another re- | sponsibility. The ChristI church laboratory is just completing a five-year survey on the air pollution of Christchurch, and the staff are also expected to follow up any oddities that crop up in their w-ork. “This is one of the most profitable ways in which research work operates," said Mr Alcorn. “We must keep alert to the unusual that crops up and find explanations for it.” This is the centennial year of the Chemistry Division. It was established in Wellington in 1865, and the Christchurch laboratory in 1925. The Chemistry Division is the largest chemistry laboratory in New Zealand, and its functions are to do long-term research in fields of econ-

omic value, to make chosen investigations for industry, to serve the needs of other Government departments, and to promote the establishment and development of research associations and of other laboratories able to give a detailed service to industry. Its research has assisted the development of the pozzolan, clay, perlite, cement and limestone industries, and the division has studied such things as the corrosion in topdressing aircraft caused by fertiliser mixtures, spontaneous combustion of wood., alkali-aggregate reactions in concrete used for dam construction. tobacco drying, spray residues on fruit, and problems in the development of geothermal-steam power. The Wellington laboratory will be opened to the public for a week in October, with special exhibitions and displays of working equipment. Something similar is planned for the Christchurch laboratory at the end of the year.