A Portland man remained in critical condition Monday and the neighbor accused of assaulting him appeared in court to face a charge of elevated aggravated assault.

Everett H. Meserve, 62, did not enter a plea during a brief appearance in Cumberland County Unified Court. No additional information was released and a judge sealed Meserve’s arrest affidavit. He was being held at Cumberland County Jail on $50,000 bail.

Meserve was arrested Sunday in connection with an assault on Rodney Cleveland, 63, who lives on the same floor of an apartment building at the corner of Danforth and High streets, Portland Police Lt. Robert Martin said.

Cleveland was found injured inside his apartment and taken to Maine Medical Center. Martin said Cleveland was in critical condition Monday afternoon.

An investigation into the assault continues and Martin said he couldn’t release further details, including what might have prompted the attack.

Meserve and Cleveland were acquainted with each other, Martin said, but he declined to elaborate on their relationship.

The apartment building where the two men lived is managed by Preservation Management Inc. and houses residents over the age of 55 in one-bedroom and efficiency apartments. A company representative did not return calls or emails Monday.

Elevated aggravated assault is a Class A felony punishable by up to 30 years in prison.

According to state statute, a person is guilty of elevated aggravated assault if the person: “intentionally or knowingly causes serious bodily injury to another person with the use of a dangerous weapon,” “engages in conduct that manifests a depraved indifference to the value of human life and that in fact causes serious bodily injury to another person with the use of a dangerous weapon,” or “with terroristic intent engages in conduct that in fact causes serious bodily injury to another person.”

Meserve has a criminal history stretching back to the 1970s, including assault and burglary convictions in the ’80s and ’90s, according to state records.