Exegesis:

holon to sunedrion (15.1; cf. the plural sunedria 13.9) ‘the whole Sanhedrin,’ ‘the entire (High) Council’: the Sanhedrin was the supreme governing body of the Jews, presided over by the current high priest, possessing both spiritual (ecclesiastical) and juridical (political) powers.

ezētoun kata (cf. 3.22) ‘they were seeking against.’

marturian (14.56, 69) ‘witness,’ ‘testimony.’

eis to thanatōsai auton ‘to put him to death’: the preposition eis ‘into’ with the infinitive of the verb, indicates here purpose – ‘they were seeking (adverse) testimony against Jesus in order to put him to death.’

thanatoō (cf. 13.12) ‘put to death,’ ‘hand over to be killed.’

kai ouch hēuriskon ‘but they were not finding (it)’: the kai is adversative.

Translation:

The whole council is in some languages ‘all the men who decided things’ or ‘all the important men,’ another way of designating membership of the council.

Sought testimony against is a very compact phrase involving two quite separate processes: (1) the seeking of persons who might testify and (2) the testimony of the men against Jesus. Moreover, the preposition against implies the statements made by Jesus’ accusers. Accordingly, in some languages this succinct expression must be somewhat expanded, e.g. ‘looked for men who would accuse Jesus’ (Highland Puebla Nahuatl) and ‘sought testimony as to the sin of Jesus’ (Tzeltal). In the first instance testimony is rendered as ‘men who would accuse,’ supplying what is essentially a subject-verb expression for the event noun of Greek and English. In the second case, against is expanded so as to indicate the hostility of the testimony.

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .