Isotope analysis
A recent development in forensic science is the isotopic analysis of hair strands. Hair has a recognisable growth rate of 9-11mm per month or 15 cm per year. Human hair growth is primarily a function of diet, especially drinking water intake. The stable isotopic ratios of drinking water are a function of location, and the geology that the water percolates through. Sr, Sr and oxygen isotope variations are different all over the world. These differences in isotopic ratio are then biologically 'set' in our hair as it grows and it has therefore become possible to identify recent geographic histories by the analysis of hair strands. For example, it could be possible to identify whether a terrorist suspect had recently been to a particular location from hair analysis. This hair analysis is a non-invasive method which is becoming very popular in cases that DNA or other traditional means are bringing no answers.
Nail (anatomy)
In humans, nails grow at an average rate of a month. Fingernails require three to six months to regrow completely, and toenails require twelve to eighteen months. Actual growth rate is dependent upon age, sex, season, exercise level, diet, and hereditary factors. 
The longest female nails known ever to have existed measured a total of 601.9 cm, an average of 60.19 cm (23.7 inches) for each fingernail. Contrary to popular belief, nails do not continue to grow after death; the skin dehydrates and tightens, making the nails (and hair) appear to grow.