Q:

Could Arsenic poisoning be detected in this setting?

I have an idea for a story , a detective fiction set in the early 1900's. I have the crime being committed as the title suggests by arsenic poisoning . 
I know that Arsenic is a form of poison that a doctor would have to suspect strongly to test for, since the symptoms of poisoning are very akin to stomach related illnesses.
I would like to know if medicine in the 20th century had advanced enough to actually detect this crime , if the detective in my story points them in this direction .

A:

"The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison. It was developed by the chemist James Marsh and first published in 1836." (Wikipedia)

There were also earlier tests used in forensic examinations in cases of doubtful deaths, for example the Metzger test, the utility of which in forensic examinations was demonstrated by Valentin Rose in 1806. The most widely used test for arsenic was discovered by Samuel Hahnemann (yes, the Hahnemann of homeopathic fame -- he was also a good chemist) at the beginning of the 19th century; this test is still in use today.
So, in the end, all this means that at the beginning of the 20th century there was no hope for a criminal to poison their victim with arsenic and escape undetected.

