N.Y. RPA. LAW § 1931 : NY Code - Section 1931: Discharge of record of ancient mortgages presumed paid

1.
  The mortgagor, his heirs or any person having any interest in any  lands
  described  in  any  mortgage  of  real  estate  in  this state, which is
  recorded in this state, or mentioned in a deed recorded in  this  state,
  and  which,  from  the  lapse of time, is presumed to be paid, or in any
  moneys into which said lands have been converted under  a  decree  of  a
  court  of  competent  jurisdiction,  and which are held in place of such
  lands to answer such mortgage, may present his petition together with an
  official search of the recording officer in whose office the mortgage is
  recorded, or a search prepared by a person duly licensed and admitted to
  practice law in this state or by a title company duly  incorporated  and
  authorized  to  transact  business  in this state showing assignments of
  record, if any, to the courts mentioned in  this  article,  asking  that
  such mortgage may be discharged of record.
    2.  Such  petition  shall be verified; it shall describe the mortgage,
  and when and where recorded, or if such mortgage is  not  recorded  that
  the  same  may  be adjudged to have been paid and to be no longer a lien
  upon the lands therein described, and shall allege that such mortgage is
  paid; that the mortgagee has, or, if there be more than  one  mortgagee,
  that  all  of  them  have been dead for more than five years; or if such
  mortgage has been assigned by an instrument in writing for that  purpose
  executed and acknowledged, so as to entitle the same to be recorded, and
  such  instrument  of  assignment  has been recorded in the office of the
  clerk of the county where the mortgaged premises or some portion thereof
  is situated, and the assignee or assignees of said  mortgage  have  been
  dead for more than five years, such petition shall state such facts, and
  no  statement  respecting  the  mortgagee or mortgagees or the names and
  places of residence of  their  heirs  shall  be  required;  or  if  such
  mortgagee  be  a  corporation  or  association, that such corporation or
  association has ceased to exist and do business as such  for  more  than
  five  years;  the  time  and  place  of his or their death, and place of
  residence at the time of his or their  death;  whether  or  not  letters
  testamentary  or  of  administration  have  been  taken out, or, if said
  mortgagee or mortgagees, or assignee or assignees at the time of his  or
  their   death  resided  out  of  this  state,  whether  or  not  letters
  testamentary or of administration have been  taken  out  in  the  county
  where  such  mortgaged  premises  are  situated;  or if a corporation or
  association, its last  place  of  business;  the  names  and  places  of
  residence,  as  far as the same can be ascertained, of the heirs of such
  mortgagee or mortgagees, or assignee or assignees; or, if such mortgagee
  be a corporation or association, then the names of one or  more  of  the
  receivers,  if  any were appointed, or of the person who has the care of
  the closing up of the business of such corporation or  association,  and
  that  such  mortgage  has  not been assigned or transferred, and if such
  mortgage has been assigned, state to whom and the facts in regard to the
  same.
    Provided, however, that if such mortgage has been  duly  assigned,  by
  indorsement  thereof or otherwise, but not acknowledged so as to entitle
  the same to be recorded, then it shall be competent for  the  court,  at
  any  time  within  the period aforesaid, upon proof that all the matters
  hereinbefore required to be stated in said petition are true,  and  that
  the  assignee of such mortgage if living, or his personal representative
  if dead, has been paid the amount due thereon, to  make  an  order  that
  such mortgage be discharged of record.
    Provided,  further,  that  in case of a mortgage which was recorded or
  adjudged to have been paid and no longer a lien, more than  fifty  years
  prior  to the presentation of such petition, if the petitioner is unable
  with reasonable diligence to ascertain the facts herein required  to  be

  stated in the petition, other than the fact of payment, the petition may
  set  forth  the  best  knowledge  and  information  of the petitioner in
  respect thereto and what efforts have been made to ascertain such facts,
  and  if  the  court  shall  be  satisfied  that  the petitioner has made
  reasonable effort to ascertain such facts, and that the same  cannot  be
  ascertained  with  reasonable diligence, it may then, in its discretion,
  proceed upon said petition as hereinafter provided.
    3. Such petition may be presented to the supreme court in  the  county
  in  which the mortgaged premises are situated, or to the county court of
  such county.
    4. The court, upon the presentation of such petition,  shall  make  an
  order  requiring  all persons interested to show cause at a certain time
  and place, why such mortgage should not be  discharged  of  record.  The
  names  of the mortgagor, mortgagee and assignee, if any, the date of the
  mortgage and where recorded, and the town or city in which the mortgaged
  premises are situate, shall be specified in the order. The  order  shall
  be  published  in such newspaper or newspapers, and for such time as the
  court shall direct. The court may also direct the order to be personally
  served upon such persons as it shall designate.
    5. The court may issue commissions to take the testimony of  witnesses
  and  may  refer  it  to  a referee to take and report proofs of the fact
  stated in the petition. The  certificate  of  the  proper  surrogate  or
  surrogates,  whether  or  not  letters testamentary or of administration
  have been issued, shall be evidence of the fact; and the certificate  of
  the clerk of the county or counties in which the mortgaged premises have
  been  situate, since the date of the said mortgage, shall be evidence of
  the assignment of such mortgage, or of a notice of the  pendency  of  an
  action  to  foreclose such mortgage, and of such other matters as may be
  therein stated; or if a notice of the pendency of an action to foreclose
  such mortgage has been filed, then his certificate  that  such  mortgage
  has  never  been  foreclosed.  Unless the allegation of payment shall be
  denied, and evidence be  given  tending  to  rebut  the  presumption  of
  payment,  arising  from  lapse  of  time,  such  lapse  of time shall be
  sufficient evidence of payment. Upon being satisfied  that  the  matters
  alleged  in  the petition are true, the court may make an order that the
  mortgage be discharged of record.