From the Wikipedia page 
Sir Richard Grey (1460? – 25 June 1483) was an English knight and the half-brother of King Edward V of England.
Grey was the younger son of Sir John Grey of Groby and Elizabeth Woodville, later Queen Consort of King Edward IV. A young child when his mother married Edward IV, Richard first appeared on the public scene when he took part in the jousts to celebrate the creation of his half-brother Richard as duke of York in 1474, a feat he repeated at the duke's marriage celebrations in 1478. Richard Grey was knighted in 1475 and was nominated four times to membership of The Most Noble Order of the Garter between 1476 and 1482, though he was never so chosen. His political role also started in 1475, the year he was knighted, when he began to serve in Wales and the bordering counties as part of the political rule of the council of his other half-brother, Edward, Prince of Wales (later Edward V). Grey served as a Justice of the Peace in Herefordshire from 1475 and sat at sessions of the peace in Hereford and Ludlow in 1476 and 1477. In 1479 he was appointed constable of Chester castle and in the same year was considered important enough for the city of Bristol to appeal to him for his aid. He served on a number of other judicial commissions in the region through the remainder of the reign of his stepfather. In 1482 he was granted the Welsh lordship of Kidwelly, and in the same year was given a greater role in the upbringing of the Prince of Wales; by the end of the reign, Grey was becoming increasingly important in the king's rule in the region. He was also being given a broader geographic field of activity, serving as constable of Wallingford Castle from 1482 and the following year being granted the Holland manors in Essex and Northamptonshire.
After the death of Edward IV, while accompanying the new king Edward V to London from Wales with their uncle Anthony Woodville, 2nd Earl Rivers, he was arrested by Richard, Duke of Gloucester (later Richard III) on 30 April 1483 at Stony Stratford and, with Rivers, imprisoned in the north of England. Within a few weeks Grey's lands and offices had been redistributed to others, although he had not been legally deprived of them. After Gloucester's accession to the throne Grey and his uncle were executed at Pontefract Castle on 25 June 1483.