An East Lyme High School graduate who posted an online threat on a social media website promising a “hail of bullets” after school break told police that he didn’t think the threat or the response to it would “escalate” to the levels they did.

Tyler McKenzie, 18, is charged with first-degree threatening and second-degree breach of peace. Wearing a dress jacket and khaki pants, McKenzie, of 49 Cubles Drive, appeared briefly in Superior Court in New London.

A warrant prepared by East Lyme police and made available Friday said McKenzie waived his Miranda rights during an interview and admitted to making the threatening post.

During a search of police records, police discovered that McKenzie had been a victim of an assault while at East Lyme High School in March 2012, the warrant said.

“At the end of his interview McKenzie stated that he wanted to add that when he posted the message he didn’t believe he wanted to harm anyone but he wasn’t sure,” the warrant said. He also told police that he had no intention of carrying out the threat.

The posting led Superintendent of Schools James Lombardo to cancel several sporting events at the high school during the holiday break while police investigated.

After his arrest Wednesday, McKenzie posted a $25,000 bond, prompting the prosecution to ask in court that strict conditions be placed on his release. Judge Omar A. Williams agreed, saying the allegations against him were serious and warranted strict supervision.

He placed the University of Connecticut student on house arrest and on GPS monitoring. He also banned McKenzie from logging onto any social media websites; ordered that he possess no weapons; that he take any prescribed medications; that his computer use be limited to school use only; and that he stay off any East Lyme school property.

Williams said McKenzie must stay on house arrest except for legal appointments, medical visits or going to classes until his next court date, Jan. 16.

McKenzie is slated to resume school on Jan. 20. UConn officials would not say if any action would be taken against him.

Defense attorney Narcy Dubicki objected to the GPS monitoring, noting that his client does not have a criminal history. After the hearing, Dubicki said neither he nor his client would comment on the pending criminal manner.

In the warrant prepared by East Lyme Officer Matthew F. Roland, the officer said that on Dec. 23 at about 11:46 p.m. he was dispatched to a residence in Niantic. The complainant had taken a screen shot of a post found on the social media site Yik Yak. The posting said, “East Lyme better get ready for the hail of bullets I’ve been bullied to [sic] long and after break I’m going to let all my anger out.”

When Roland went to the site the posting had been removed, the warrant said.

According to law enforcement guidelines on Yik Yak’s website, Yik Yak keeps a log of the Internet Protocol (IP) addresses, GPS coordinates and time and date related to each message. Under federal law, Yik Yak may provide information to law enforcement if requested in response to an emergency situation.

Roland contacted Yik Yak’s legal department, which provided him with GPS coordinates and an IP address. Officials at the social media site said the message was posted Dec. 23 at 11:26 p.m., about 20 minutes before the complaint to police.

Using an Internet mapping service and the GPS coordinates, Roland found that the post was placed in the area of 48 Cubles Drive. Roland also discovered that the IP address was owned by mycingular.net, a division of AT&T. AT&T told the officer that the IP address was assigned to a cell phone, the warrant said.

Detective Humberto Morales of the Eastern District Major Crime Squad used MapQuest to determine that 48 Cubles Drive is 2.3 miles away from the complainant’s house and one mile from the nearest tower, owned by AT&T, at 93 Roxbury Road.

The company confirmed that its tower would have been used to transmit the Yik Yak message, the warrant said.

On Christmas Day, Roland went to 48 Cubles Drive and spoke to a 60-year-old female resident who told police that she neither posted the threat nor had a Yik Yak account. Four days later, an FBI analyst assisting in the case found that McKenzie had an active Yik Yak account and lived across the street from the GPS coordinates, at 49 Cubles Drive.

FBI Agent Marc LaFrance obtained a federal search and seizure warrant to obtain Yik Yak content and GPS data connected to McKenzie’s cell phone number. An analysis of the information obtained showed that from Dec. 20 to Dec. 24 multiple posts were placed from the area of 49 Cubles Drive and that the cell phone hit off the Roxbury Road tower during the same time frame.

Based on that information, a federal search and seizure warrant was executed on Wednesday at McKenzie’s home. His cell phone was seized at the time. No weapons were registered in his name and no weapons were discovered at the time of his arrest, the warrant said.

School officials said students should still expect a greater police presence, along with additional screening procedures, at schools on Monday. Parents earlier this week were notified that backpack checks would be made at the middle school and high school.

i.larraneta@theday.com

Twitter: @larraneta