Alonso announced his decision to retire Saturday, someone reports.

Alonso signed a one-year contract with the Saints on Thursday after a successful workout with the team earlier in the day, Jeremy Fowler of ESPN.com reports.

The 49ers waived Alonso (knee) with a failed physical designation Monday, Adam Caplan of SiriusXM NFL Radio reports.

Alonso (knee) had his practice period expire Saturday and will remain on the PUP list for the rest of the season, per the NFL's official transaction log.

Alonso (knee) and a conditional fifth-round pick were traded from the Saints to the 49ers in exchange for linebacker Kwon Alexander (ankle) on Monday, Tom Pelissero of NFL Network> reports.

Alonso (knee) received the return designation and should practice this week, Field Yates of ESPN reports.

The Saints placed Alonso (knee) on the reserve/PUP list Saturday, Nick Underhill of NewOrleans.Football reports.

Alonso (knee) was placed on the active/physically unable to perform list Saturday, Nick Underhill of NewOrleans.Football reports.