Psychological autopsies are usually only done with samples of survivors of a decedent who died by suicide. Suicide attempt survivors are available to speak to their "lived experience." As for using the families who have experienced a suicide as respondents, I would suggest that you (1) familiarize yourself with the psychological autopsy literature (including the critiques), (2) look into the growing literature on suicide loss survivors to acquaint yourself with some of the possible pitfalls to using them as a source of data on suicidality, and (3) having done those two steps give some thought as to what you mean by "suicidality" operationally and if those close to the victim can really provide valid information on their mental status, emotional state, etc., and other subjective and intangible factors as opposed to variables such as marital status, legal and financial problems, employment, etc., which are more readily and accurately recalled by those close to the victim.  

I seem to agree with Tony. Hong Kong currently just had a government committee to study so-called reasons for "high suicide" in school children especially in universities. What I read, they studied about 30-40 real cases of such incidence for past certain years. One of the important element I realised was the availability of reliable records. In Hong Kong, I was told when a person is categorised as under "suicide" category, the Coroners Court or the relevant law enforcement department will need to build a case file - which include normal historical stuff, interviews with family members, historical medical records, interview with school friends, relatives, etc. Think there is a protocol to this. Thus, to the best belief, memory and accuracy of the note taker and the one being interviewed, they collate certain amount of information which in this case allowed the researchers to do quite a good psychological autopsy. However, the terms of references need to be clear. In the above, what I read was that they are tasked to find out reasons of school-children (defined as in terms of reference) committing suicide (I would assumed "completed suicide" or it will not involve the coroners court) and to come out with certain recommendations for the government of Hong Kong.

In your case, I would think the objective of the study needs to be established. I have read some iiterature on experience of closed ones under "grieve" subject matter, and some under "thanatology". Perhaps, I am new, but you mentioned: "suicidality exploring the lived experience of the current participants (approx 30) as well as exploring those lost to suicide via psychological autopsy (approx 10 families)". It is not very clear what aspects you want to study and who are the participants. As you noted that you are trying to study/explore or measure some sort of "emotions" to some people who have been subjected to certain life event, I think there are not many quantitative approach that I know. Psychological autopsy is one approach they have - and also if you have identified the participants, you need to see any socio-demographics that may make the experience very different, also what kind of information you can have, or what kind of "thematic" approach you can have - for e.g. comparing experience of XYZ between youth suicide and suicide involving the elderlies. Just some thoughts ... Regards.

I attach here my study, described in these articles. The main point I wish to stress is that suicidal attempters are very different. People with denial of attempt, who admit their attempt and with several attempts in the anamnesis are very different. And it is if not to take alcohol/ drug abuse, those people are also tend to tell different stories. You can read about it in the literature, read Thomas Joiner works on the matter of single and multiple attempts.

Article Terror Management After a Recent Suicide Attempt

Article Defences Against the Fear of Death in Postsuicide

Chapter Friend or Foe? Escape from Death, or Death as an Escape

Thank you everyone for your answers and links to articles, all very useful :)