It depends on the situation and how badly they want you dealt with. According to the Elders handbook a df'ing situation can be held in abeyance if there is no immediate spiritual threat from the individual or his/her situation is not well known in the community and the individual can't be reached by reasonable means
If they really are out to get you then you can be df'ed in absentia if they can prove what you are being accused of via witnesses or other evidence that they deem appropriate. It honestly depends on how much they "want to get you". Anything can be swept under the carpet if they want to.