What are the "signs of grief" for which a pastor should be on the look out?

So, in my seminary pastoral care class, I remember being taken to a funeral home, and walked through the mechanics of a funeral. During that visit, I was told that "everyone's grief process is different," and I have seen wide variation in this. I have seen people who have lost sisters and mothers grieve for several weeks and be fine. I have seen at the upper end four to six months of being seemingly stuck on the loss. Later (in the same class I should add!), I was admonished that as a pastor, I should be on the lookout for those who are "stuck in grief." When I pressed on this – namely 'what are the signs that someone is stuck in grief,' I was never given a satisfactory answer. While the Psalms describe the emotions that many feel when grieving (as well as comfort), are there any lists by classic pastoral care givers (e.g. Thomas Owens, patristic sources, the Reformers, etc... – *not* just Ms. Kubler-Ross please) of the signs that a pastor should be on the lookout that someone really is "stuck in grief?"