εν preposition
en  en: in, at, (up-)on, by, etc.
ταυτη demonstrative pronoun - dative singular feminine
houtos  hoo'-tos: the he (she or it), i.e. this or that (often with article repeated) -- he (it was that), hereof, it, she, such as, the same, these, they, this (man, same, woman), which, who.
γαρ conjunction
gar  gar: assigning a reason (used in argument, explanation or intensification; often with other particles)
εμαρτυρηθησαν verb - aorist passive indicative - third person
martureo  mar-too-reh'-o: to be a witness, i.e. testify
οι definite article - nominative plural masculine
ho  ho: the definite article; the (sometimes to be supplied, at others omitted, in English idiom) -- the, this, that, one, he, she, it, etc.
πρεσβυτεροι adjective - nominative plural masculine
presbuteros  pres-boo'-ter-os: older; as noun, a senior; specially, an Israelite Sanhedrist (also figuratively, member of the celestial council) or Christian presbyter -- elder(-est), old.