A Dorchester man is being held in Falmouth on $25,000 cash bail after allegedly sexually assaulting a teenaged traveler on a Steamship Authority vessel as it made passage from Martha’s Vineyard to Woods Hole Monday afternoon.

Bruno S. DeJesus, 20, of Dorchester was arraigned in Falmouth district court Tuesday before the Hon. Paul Pino on two counts of rape. Bail was set at $25,000. Further conditions include GPS monitoring and to stay away from and have no contact with the alleged victim.

A probable cause hearing has been set for June 29.

The alleged assault occurred shortly before 5 p.m. in the back of a commercial delivery box truck on a late afternoon ferry, according to press releases from the Cape and Islands district attorney’s office.

The victim is an 18-year-old female, according to a separate state police press release.

The attack was reported to Falmouth police after the ferry docked in Woods Hole. But Mr. DeJesus had already left the SSA vessel as a passenger on the commercial box truck, the DA’s statement said, prompting a wider search.

After the attack was reported, a description of the truck was broadcast and a state police trooper from the Bourne barracks located and stopped the vehicle on Route 28 in Falmouth, according to state police. Following investigation by the state police detective unit for the Cape and Islands, Mr. DeJesus was charged with two counts of rape and held on $25,000 cash bail Monday night.

A statement of facts given by an assistant district attorney Brian Degan during Mr. DeJesus’s arraignment Tuesday provided further details on the incident.

According to the assistant district attorney, Mr. DeJesus works for an appliance delivery company that was making shipments on Martha’s Vineyard Monday morning. The defendant was a passenger in the truck that arrived at the Vineyard Haven ferry terminal around noon, and was in the standby line with the vehicle driver until approximately 4 p.m. before obtaining a spot on a vessel, according to the statement.

A recent ransomware attack has shut down the SSA reservation system, forcing all vehicles without prior reservations to travel on standby.

In his statement the district attorney described events that allegedly took place on board the vessel, including an encounter between Mr. DeJesus and a female in the concession area, and later an alleged assault and rape in the back of the box truck.

The victim provided testimony to police, including details about the truck and appearance of the perpetrator, the district attorney said, that led to the arrest after Mr. DeJesus had allegedly walked off the vessel as a passenger and met the vehicle driver in Woods Hole. The truck was later apprehended by police.

The assistant district attorney requested $50,000 bail.

Sean Murphy, a bail attorney representing Mr. DeJesus at arraignment, raised concerns with the police report and statement of facts, and requested that the court order the Steamship Authority and law enforcement to preserve evidence, including SSA video cameras and cell phone videos from Mr. DeJesus’s phone.

Judge Pino set bail at $25,000, and granted the request.

In an emailed statement, SSA spokesman Sean Driscoll said the boat line was cooperating with state police in the investigation.