Over a third of newly employed corrections officers at New York City’s Rikers Island jail “were not fit for fit for service and should not have been hired”, the New York City Department of investigation (DOI) has found.

The public findings in the report, published on Thursday, examined a random sample of 153 files of fresh recruits and found that 10 had been arrested more than once, 65 had psychological issues and others had gang affiliations as well as unexplained relationships with current inmates.

The investigation concluded that the state of the notorious jail facility, which houses 15,000 juvenile and adult inmates, indicated significant shortcomings in New York’s department of corrections’ (DOC) screening process, which the city’s newly appointed corrections commissioner, Joseph Ponte, has pledged to reform.

In one case the department hired an officer who pleaded guilty in a domestic violence case. Another recruit admitted to having close ties to a gang member.

In another case, the department hired an officer whose psychological test results indicated “low personality development”.That application was initially declined, but then accepted when the DOC deputy commissioner intervened. There were no detailed notes to explain the reversal, but the officer’s file described the officer as a “family friend of Norman Seabrook [president of the Correction Officers Benevolent Association]”.

The union president did not immediately respond to a request for comment from the Guardian.

Rikers has been at the centre of an ongoing controversy after a damning report from the US attorney’s office in August 2014 revealed a “deep-seated culture of violence” in juvenile detention facilities at the jail.

The jail, which is now being sued by the Department of Justice in a civil rights case , has announced a raft of reforms, including abolishing solitary confinement of inmates under the age of 21.

On Tuesday, the Associated Press revealed that Rikers corrections officers filed a record number of “use of force” reports last year.

The DOI report calls on the corrections department to introduce “an aggressive recruitment strategy and clear disqualification standards to improve the applicant pool”.

The DOI commissioner Mark Peters said in a joint statement with Ponte that the investigation had exposed a “shockingly inadequate screening system, which has led to the hiring of many officers that are underqualified and unfit for duty”.

“Applicants with a history of gang violence and gang affiliations should not be patrolling our jails. Positions as law enforcement officers demand better,” Peters said.

Ponte added: “Improving staff recruitment, training and retention is a key part of my agenda of meaningful reform. My earliest actions as commissioner included providing new leadership for our staff recruiting and training operations.”