That’s one angry nerd.

In June, Conor Lahiff lost his job as a desktop and network manager at Whittier Regional Vocational Technical High School in Haverhill — but he didn’t take the termination sitting down.

Instead, Lahiff used his administrative network privileges to deactivate 1,200 Apple IDs from the school’s account with the company — which the school used to manage its student, faculty and staff resources — as well as another 1,400 school-affiliated Apple accounts, according to the criminal complaint filed in federal court in Boston.

He also aimed his ire directly at his superior, the unnamed director of the school’s department of technology and information systems, as well as an IT helpdesk clerk, by deactivating their school administrative accounts and deleting their administrative accounts with an IT security vendor, the complaint states. He also shut down the school’s phone system for some 24 hours. It all amounted to an estimated loss of more than $5,000.

Authorities arrested Lahiff, 30, on Wednesday. That same day, he entered an agreement to plead guilty to one count of unauthorized damage to protected computers, a charge which carries a sentence of up to 10 years in prison and a fine of up to $250,000. He is scheduled to plead guilty in federal court in Boston the morning of Dec. 13.