SOMERS, N.Y. - Charges against a second teen arrested in January’s school-bus vandalism were upgraded this week to felony-level criminal mischief.

Jonathan L. Delfa, 18, was arraigned in Somers Town Justice Court on the more-serious charges Monday, immediately following an appearance by fellow Somers High School senior Jonas M. Moseby. Justice Denis J. Timone ordered both to return to the court July 18.

Moseby, a one-time honor roll student, and Delfa, a former varsity football standout, are accused of being the marauders who inflicted thousands of dollars in damage to the Somers Central School District bus fleet in a late-night rampage at the high school in early January. Both graduated from Somers High School this month.

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Arrested after a months-long investigation on June 21, Moseby was charged with second-degree criminal mischief, a D felony punishable by up to seven years in state prison.

Delfa, picked up by the state police on June 10, had not been named and was originally charged only with fourth-degree criminal mischief, an A misdemeanor. That complaint could have landed Delfa, at worst, in the county jail for up to a year and left him eligible for youthful-offender status. But in court on Monday, Assistant District Attorney Marissa Morra-Wynn elevated the charge against Delfa to the same felony Moseby faces.

The two are accused of slashing bus tires, shattering windows and discharging fire extinguishers in methodically vandalizing 43 school buses. In addition to the damage, estimated at more than $29,000, the destructive spree crippled the school-bus fleet and forced a district-wide closing Jan. 4.

In an email to parents last week, Dr. Raymond Blanch, the school superintendent, said of the vandalism: “This incident caused a great disruption for both parents and students, and we are grateful for your patience and cooperation during that time.”

Blanch said he was “disappointed to learn that Somers students were charged in this incident.”

After his June 21 arrest, Moseby was originally arraigned at North Salem Justice Court, and then released on $10,000 cash bail. Timone continued the bail and declared Moseby effectively under house arrest—free to leave only to go to work—until his hearing in three weeks.

Delfa, who had been released in his parents’ custody after his June 10 arrest, remained free in that capacity pending his July 18 return.