Eachtime you kill a innocent player (read: blue). This player gets the chance to place 1 murdercount on you. (technically 2 murdercounts, 1 long one and 1 short one, but it is explained below).

Note: thieves can never place murdercounts as long as they are part of the thieves guild. Wether they are blue or grey, they can never place a murdercount (attacking a innocent thief (blue) is however a criminal act and will make you grey).

How can I see how many murdercounts I got?

By typing: I must consider my sins.

What is a long term murdercount?

Long term murdercounts wear off each 40 hours (in game hours). After having 5 (or more) long term murdercounts your status becomes red (read: red name). This will mean you can get attacked/killed/looted by other players freely.
You can still enter towns* and your bankbox as long as you havn't recently commited a criminal act.

* please note that red characters can't enter town/guardzones on the T2A shard.

What is a short term murdercount?

Short term murdercounts wear off each 8 hours (in game hours). Short term murdercounts affect statloss*. After having 5 (or more) short term murdercounts you will become in statloss. This means that eachtime you resurrect yourself while in this state, you will suffer statloss.

Can I buy off murdercounts?

No, if you die on your murdering character and do not wish to suffer statloss, there is only 1 thing to do: macro off your murdercounts while being a ghost.