Jara was the name of a hunter. He hit Krishna on his toe, when the latter was lying in a bush under atree in the forest during his last moments on the earth. ( Jara was also the name of a demoness, connected with the story of the Magadha king Jaraasandha. See the link Jara. )
After the geat war of Mahaabhaaratham was over, Gaandhaari lamented the loss of her hundred sons and in her bitter grief, she cursed Krishna that his clan and kinsmen too would perish due to an internal strife like the Kouravas did. Krishna knew that the curse was only a promotor of the future as destined and remained silent.
Thirty six years later, Krishna sensed the omens of destruction of the Yaadavas. Incidentally, some great sages visited dvaaraka to see Krishna. At that time, some unruly Yaadava youths made up Krishna's son Saamba like a girl and asked the approaching sages to predict if the girl would give birth to a girl or a boy. The enraged sages cursed that the false girl would deliver a pestle that would destroy their race.
The incident was reported to Krishna but he remained silent as he did not wish to interfere with destiny'd course. Their king Ugrasena, however, attempted to avoid the possible danger by that pestle and ordered his men to rub it off against the stones in the sea to powder it away. They did accordingly . In the end, a small piece remained which could not be conveniently held with hand to rub. They threw the piece away into the sea . All the powder of the pestle that fell into the water and the last thrown away piece too were carried to the shore by the waves of the sea water. The powder settled on the land and grew into a kind of bullrush frass -Eraka- grew. The piece of the pestle was found by a hunter Jara who put it as a tip to his arrow.
After all the Yaadavas were slain among themselves, Balaraama retired to his original abode. Krishna too settled under a tree and sank into his yogic trance, preparing to leave his mortal for. At the same time, the hunter Jara came that way. He mistook Krishna's foot to be the ear of a deer and hit at it with his arrow which bore the piece of the pestle as its tip. Hit by that aroow, Krishna left his body, aonsoling the repenting hunter Jara. Thus the unknown hunter Jara was the last person to see Krishna alive!
"After praying to Naaraayana, Nara, Sarasvathi and Vyaasa, then one should read the Jayam."
DEDICATED TO MY DEAR NIECE VYSHNAVI KRISHNA