ever ▁came ▁in ▁contact ▁with ▁that ▁piece ▁of ▁evidence ▁is ▁account able ▁for ▁what ▁happens ▁to ▁it . ▁This ▁prevents ▁police ▁officers ▁and ▁other ▁law ▁officials ▁from ▁cont amin ating ▁the ▁evidence ▁or ▁taking ▁the ▁piece ▁of ▁evidence . ▁ ▁Example ▁An ▁example ▁of ▁chain ▁of ▁cust ody ▁would ▁be ▁the ▁recovery ▁of ▁a ▁blo ody ▁kn ife ▁at ▁a ▁murder ▁scene : ▁Officer ▁Andrew ▁collect s ▁the ▁kn ife ▁and ▁places ▁it ▁into ▁a ▁container , ▁then ▁gives ▁it ▁to ▁for ens ics ▁techn ician ▁Bill . ▁For ens ics ▁techn ician ▁Bill ▁takes ▁the ▁kn ife ▁to ▁the ▁lab ▁and ▁collect s ▁finger print s ▁and ▁other ▁evidence ▁from ▁the ▁kn ife . ▁Bill ▁then ▁gives ▁the ▁kn ife ▁and ▁all ▁evidence ▁gathered ▁from ▁the ▁kn ife ▁to ▁evidence ▁cl erk ▁Char l ene . ▁Char l ene ▁then ▁stores ▁the ▁evidence ▁until ▁it ▁is ▁needed , ▁document ing ▁everyone ▁who ▁has ▁accessed ▁the ▁original ▁evidence ▁( the ▁kn ife , ▁and ▁original ▁copies ▁of ▁the ▁lifted ▁finger print s ). ▁ ▁The ▁chain ▁of ▁cust ody ▁requires ▁that ▁from ▁the ▁moment ▁the ▁evidence ▁is ▁collected , ▁every ▁transfer ▁of ▁evidence ▁from ▁person ▁to ▁person ▁be ▁documented ▁and ▁that ▁it ▁be ▁prov able ▁that ▁nobody ▁else ▁could ▁have ▁accessed ▁that ▁evidence . ▁It ▁is ▁best ▁to ▁keep ▁the ▁number ▁of ▁trans fers ▁as ▁low ▁as ▁possible . ▁ ▁In ▁the ▁court room , ▁if ▁the ▁def endant ▁questions ▁the ▁chain ▁of ▁cust ody ▁of ▁the ▁evidence ▁it ▁can ▁be ▁proven ▁that