A Hempstead man beat up his grandmother and uncle in a robbery attack that was so serious that Nassau homicide detectives got involved, authorities said.

Jarmell Richardson, 38, was being held on three counts of second-degree assault and first-degree robbery, officials said.

He was intoxicated when he went to his relatives’ Cedar Street home in Hempstead Village to rob them just after 3 a.m. Tuesday, authorities said.

He beat his grandmother and stabbed his uncle, Hempstead police said.

When his uncle asked why he was in the house, Richardson grabbed a barbecue fork and scissors and wounded the man in the head and ears, according to the complaint filed by Nassau homicide detectives.

Court documents show the grandmother, 88, was struck several times in the head and face, and underwent eye surgery at Winthrop-University Hospital in Mineola. She was in critical condition at the time, but police later said she had stabilized and was expected to survive.

advertisement | advertise on newsday

Richardson’s uncle was also treated there, the complaint said.

Detectives said they have sworn statements against Richardson, including from a witness, the court documents said.

Hempstead police arrested Richardson shortly after the attack.

Richardson was arraigned Wednesday and held in lieu of $260,000 bond or $130,000 cash bail. He was represented by Legal Aid, which has a policy of not commenting on criminal cases. His family could not be reached Thursday night.

Two protection orders have been issued against Richardson, prosecutors said.