Userkare is believed to have been a proponent of the group that, at least according to Manetho, murdered Teti. He is, however, mentioned in several king-lists, which could indicate that later generations did consider his kingship to have been legitimate. The fact that none of the few traces he left behind seems to have suffered effacement, would also point towards his reign having been accepted by his successors.
Userkare is belived to have been a son of Teti with either Khuit or Khent(kaus III). If Khent(kaus III) was indeed Userkare’s mother and if the reconstruction of her name is correct, Userkare may have been related to the royal family of the earlier 5th Dynasty, when two queens bore that same name: Khentkaus I and Khentkaus II.
In the Turin King-list, there is a lacuna between Teti and Pepi I, large enough to have fitted an entry about Userkare.
He at least started or undertook some larger building projects, as shown by an inscription mentioning a workforce.
It is not known how Userkare's reign ended. If indeed he belonged to the party that had Teti murdered, than the fact that he was succeeded by Pepi I, a son of Teti, at least indicates that his coup was not successful for long. There has been no pyramid-complex that has been identified as his.