Tacitus, Annales iv, 45: murder.

Tacitus is an author still worth reading for his vividness of language and eye for details. In this chapter he describes the murder on Lucius Piso, a praetor in Spain. He investigated fraud amongst the Termistine tribe. Little is known about this tribe, but their capital was the city of Termes, near Numantia.  The fraud was the disappearance of tax revenues - revenues under Roman control. My guess is that rather having these revenues send to Rome or spend on Roman prestige projects, the Termistines wanted to have it for their own purposes. From a Roman perspective, Tacitus of course sees this as an act of rebellion and the murder as a terrible crime.  

Tacitus, Annales, iv, 45

[45] Isdem consulibus facinus atrox in citeriore Hispania admissum a quodam agresti nationis Termestinae. is praetorem provinciae L. Pisonem, pace incuriosum, ex improviso in itinere adortus uno vulnere in mortem adfecit; ac pernicitate equi profugus, postquam saltuosos locos attigerat, dimisso equo per derupta et avia sequentis frustratus est. neque diu fefellit: nam prenso ductoque per proximos pagos equo cuius foret cognitum. et repertus cum tormentis edere conscios adigeretur, voce magna sermone patrio frustra se interrogari clamitavit: adsisterent socii ac spectarent; nullam vim tantam doloris fore ut veritatem eliceret. idemque cum postero ad quaestionem retraheretur, eo nisu proripuit se custodibus saxoque caput adflixit ut statim exanimaretur. sed Piso Termestinorum dolo caesus habetur; quippe pecunias e publico interceptas acrius quam ut tolerarent barbari cogebat.

Isdem consulibus: under the same consuls, i.e. Lentulus Gaetulicus and C. Calvinus in 26 AD

facinus admitto: to commit a crime

citer citra citrum: at this side (citeriore Hispania: seen from Rome, so the east)

agrestis –is (m,): peasant

praetor: in the provinces of Rome, a praetor was a governor,

incuriosus: careless

ex improviso: unexpectedly

adorior adortus: to attack

in mortem adficio: to kill

pernicitas –atis (f.): swiftness

saltuosus: covered with woods

attingo attigi attactum: to reach

per derupta et avia: by precipices and wildernesses

frustror frustratus: to elude, deceive (sequentis = sequentes)

fallo fefelli falsum: to deceive

prenso (prehenso) (-are): to grasp, seize

pagus: district

cuius foret cognitum = cognitum (erat) cuius foret: it was found out of whom (it) was.

reperio repperi repertum: to find, discover

edo edidi editum: to disclose

conscius: partaker, accomplice

adigo adegi adactum: to compel

sermone patrio: in his own language (probably Celtiberian)

frustra: in vain

clamito: frequentative of clamo `he kept screaming’

adisterent socii et spectarent: irrealis

elicio elicui (-ere): elicit, bring out

postero die

questio –onis (f.): interrogation

eo nisu…ut: with such an effort…that

proripio proripui proreptum: to rush out (but here also the meaning eripio `to break out’)

saxoque caput adflixit: and dashed his head to a stone

exanimor: to die

Piso  caesus  habetur: Piso is thought to be killed

pecunias a publico ereptas: money embezzled from the public purse

quippe: because

acrius: more zealously

cogebat: tried to collect

Translation by Alfred John Church and William Jackson Brodribb (1876, note that the translation is not always accurate.)

While the same consuls were in office, an atrocious crime was committed in Nearer Spain by a peasant of the Termestine tribe. Suddenly attacking the prætor of the province, Lucius Piso, as he was travelling in all the carelessness of peace, he killed him with a single wound. He then fled on a swift horse, and reached a wooded country, where he parted with his steed and eluded pursuit amid rocky and pathless wilds. But he was soon discovered. The horse was caught and led through the neighbouring villages, and its owner ascertained. Being found and put to the torture that he might be forced to reveal his accomplices, he exclaimed in a loud voice, in the language of his country, that it was in vain to question him; his comrades might stand by and look on, but that the most intense agony would not wring the truth from him. Next day, when he was dragged back to torture, he broke loose from his guards and dashed his head against a stone with such violence that he instantly fell dead. It was however believed that Piso was treacherously murdered by the Termestini. Some public money had been embezzled, and he was pressing for its payment too rigorously for the patience of barbarians.