Order of decedent's succession:
Spouse, issue (children), parents, siblings, grandparents (rare), first cousins, first cousins once removed.

Checklist Of Sources Of Information To Prove Kinship and Satisfy The Requirements of "Diligent and Exhaustive Inquiry" (Queens County Surrogate's Court 4/23/1994)

  1. Interested/ relatives (but see CPLR 4519)
  2. Friends, neighbors, landlords, community and business associates, last and former employers, pension and retirement records.
  3. Current occupants of former residence and business addresses.
  4. Post Office FOI request for forwarding information
  5. Membership secretaries of known clubs, unions, social organizations, business associations
  6. Professional organizations: bar, AMA, CPA, realtors and trade associations
    sources: NYPL, NY Medical Academy, Martindale-Hubbell, AIA, unions, engineers etc.
  7. Agencies regulating or liscencing employment (Taxi and Limousine Commission, Dept. of Consumer Affairs, State Dept. of Education).
  8. (decedent's) Clergyman, doctor, lawyer, accountant or insurance broker.
  9. Funeral director, cemetery records, tombstone inscriptions, funeral visitors, log.
  10. Health Dept., birth and death records, hospital records
    sources: NYC DoH b.1910-date, d.1949-date; indices @ Municipal Archives and NYPL
  11. Marriage certificate indices.
    sources: City Clerk 1930-date; Municipal Archives; NYS DoH indices @ NARA to 1949, NYPL
  12. Church/synagogue, baptismal records, family bible (but see hearsay and ancient document rules), (personal effects, correspondence; hearsay exception: pedigree declarations) other family diaries, photo albums, portrait and photograph inscriptions.
  13. Surrogate's Court records (petitions in estate of known relatives), local probate court records, adoption proceedings, judgment records, real property records (grantor-grantee index and statement in deeds and mortgages; contact attorney on deed in).
  14. Voting records sources: NYC Borough Boards of Elections; NYPL; Municipal Archives
  15. Federal and state census records.
  16. IRS and NYS Tax Commission records (returns include social security #, address, employer information).
  17. Social Security Administration; social service agencies (homeless, etc.).
  18. Bank records (signature cards often include pedigree clues).
  19. Public and private school and alumni records.
  20. Military, draft board, Veterans' Administration and VA Hospital records.
    sources: National Personnel Records Center, 9700 Page Blvd., St. Louis MO 63132
  21. Police, probation and prison records.
    sources: federal Bureau of Prisons
  22. Naturalization records, passport applications, ship's registers, manifests and steamship passenger lists.
    sources: NARA, NYPL; US State Dept. (passports)
  23. Newspaper obituaries/death notices.
    sources: NYPL, BPL etc.
  24. Telephone and City (address) directories, local and national databases: persons with similar names is similar locales.
    sources: NYPL; on-line services
  25. Department of Motor Vehicles (driver's license applications, auto registration)
  26. Public Administrator.
  27. Advertise for information in local newspapers and trade publications
  28. Consular offices, embassies
  29. Genealogy resources of the Mormon Family History Libraries
  30. Retain a professional genealogist for all of the above.
    sources: Association of Professional Genealogists directory, Metro council

NEW YORK STATE PROBATE due diligence requirements, (NYS 22, NYCRR SR-12 §207.16) as of 10/3/2000 (disclaimed, as information only, I'm NOT a lawyer)

(d) If the petitioner alleges that any of the distributees or others required to be cited are unknown or that the names and addresses of some persons who are or ma be distributees are unknown, petitioner must submit an affidavit showing that her or she has used due diligence in endeavoring to ascertain the identity, names and addresses of all such persons. Compliance with this due diligence requirement is not intended to burden the estate with costly or overly time-consuming searches. Absent special circumstances, the affidavit will be deemed to satisfy the due diligence requirement if it indicates the results obtained from the following:

(If the petitioner alleges that any of the distributees are unknown, petitioner must submit an affidavit showing due diligence to ascertain the identity, names and addresses. Compliance is not intended to be costly or overly time-consuming searches. Absent special circumstances, the affidavit will satisfy the due diligence requirement if it indicates the following:

  1. Examination of the decedent's personal effects, including address books:
  2. Inquiry of decedent's reltives, neighbors, friends, former business associates and employers, the post office and financial institutions:
  3. Correspondance to the last known address of any missing distributees:
  4. Correspondance or telephone to, or internet search for, persons of same or similar name in the area where the person being sought lived:
  5. Examination of the records of the motor vehicle bureau and board of elections of the state or county of the last known address of the person whose whereabouts is unknown.

In probate proceedings, the court may accept, in lieu of the above, an affidavit by decedent setting forth the efforts that he or she made to ascertain relatives.

Example: if someone died with no surviving children, spouse, parents then the family will be traced to all the living first cousins, resulting a substantial genealogical record in the probate file.