The Lions announced that they have signed five undrafted rookie free agents:
WR Demir Boldin
C Dan Gerberry
DT John Gill
LB Andrew Downey
K Swayze Waters
Neither Otis Wiley nor Daniel Holtzclaw is on this list, so I'm not exactly sure what happened to them. There was never any official confirmation about either player, but multiple outlets reported the Wiley signing, so I'm not exactly sure what's up.
UPDATE: The players signed aren't the only ones attending the camp. There are other rookies attending on a tryout basis, so that is probably what happened to Wiley and Holtzclaw.
UPDATE II: You can now find a list of "rookie orientation tryout players" by clicking the link at the top of the story. Daniel Holtzclaw is on the list, but Otis Wiley is not.