Chris Bucchere, the cyclist who fatally struck a 71-year-old pedestrian after "plowing" in to a crosswalk at Market and Castro Streets has been charged with felony vehicular manslaughter for his actions back in March. According to the Chronicle, a judge issued the warrant for Bucchere's arrest Wednesday afternoon and District Attorney Gascón has scheduled a press conference for 10:30 a.m. to announce the charges.

Bucchere is expected to be booked before the end of the week and he could be arraigned as early as Friday.

As Matier & Ross report, their sources inside the Hall of Justice say prosecutors have concluded that Bucchere was "grossly negligent in his riding" when he crashed in to 71-year-old Sutchi Hui on Castro Street. Prosecutors still believe that the light was yellow when Bucchere entered the intersection with Market Street. However, as noted earlier, a motorist (read that as anti-cyclist, if you like) reported seeing Bucchere run a couple red lights and blow some stop signs on Divisadero, which turns into Castro Street southbound towards Market.

Likewise, the DA's office appears to be latching on to GPS tracking data and traffic surveillance footage as evidence. The Strava iPhone app Bucchere was using to record his speedy ride back from the Marin headlands that morning allegedly clocked him doing more than 35 mph despite the 25 mph speed limits. (There's some debate about the accuracy of the iPhone data, though.) The surveillance camera, if you recall, showed Bucchere hunched down in a speed tuck and making little effort to stop as he went through the intersection.

As for why it took so long to file the charges? Sources inside the investigation told the Chronicle's mustachioed duo (who have been doggedly pursuing this killer cyclist story) that interviews were conducted with at least 10 potential witnesses.

Look for updates following District Attorny Gascón's press conference later this morning.

Previously: Cyclist Who Killed Castro Pedestrian Could Face Felony Manslaughter Charges, All Chris Buccher/Castro Cyclist coverage on SFist.