Interpreter Derlyn Roberts, 53, has a prior fraud conviction. Her signs were gibberish

An American Sign Language interpreter has baffled the hearing impaired by delivering gibberish gestures during a crucial police press conference in the Tampa serial killer case.

As Tampa police Chief Brian Dugan announced the arrest of Howell Donaldson Wednesday night, interpreter Derlyn Roberts was there beside him, making signs that made no sense.

State records reviewed by DailyMail.com show that 53-year-old Roberts, who also goes by the name Derlyn Glover, served a five-year prison sentence on a felony fraud conviction and was released in April of 2016. She also has prior convictions for grand theft and burglary.

'She sat up there and waved her arms like she was singing Jingle Bells,' Rachell Settambrino, who is deaf and teaches American Sign Language at the University of South Florida, told the Tampa Bay Times through an interpreter.

Interpreter Derlyn Roberts (left) made no sense to hearing-impaired viewers during a crucial police press conference on Wednesday, where charges were announced in a serial killer case

Among the things Roberts signed, according to Settambrino, was the following: 'Fifty-one hours ago, zero 12 22 (indecipherable) murder three minutes in 14 weeks ago in old (indecipherable) murder four five 55,000 plea 10 arrest murder bush (indecipherable) three age 24.'

Howell Donaldson, 24, was charged in the four fatal shootings that have rocked Tampa

In fact, the chief was providing a timeline of the four shootings, and describing how his agency had received some 5,000 tips before arresting the 24-year-old suspect.

'I was disappointed, confused, upset and really want to know why the city of Tampa's chief of police, who is responsible for my safety ... did not check her out,' Settambrino said.

The city was just as confused.

Tampa Police Department spokeswoman Janelle McGregor told the Tampa Bay Times officials are conducting a review because they didn't even request an interpreter for the Nov. 28 news conference.

At the next day's follow-up news conference, a different interpreter, Ben Zapata, was beside the chief.

It is the most recent example of an apparently unqualified signer appearing at news conferences.

In September, as Hurricane Irma approached Florida and officials announced a mandatory evacuation, an interpreter in nearby Manatee County began signing words like 'pizza', ''monster' and 'bear', along with other gibberish.

Police say they did not request an interpreter for the press conference, and are baffled as to why Roberts (circled) was there signing gibberish

Manatee County officials later said they were in a pinch and called on a county employee who had an understanding of sign language because he communicates with his deaf brother.

However, it quickly became apparent he was in over his head. The deaf community demanded an apology and the video of the news conference went viral.

In 2013 in South Africa, a fake interpreter appeared beside former President Barak Obama and other world leaders during a memorial service for Nelson Mandela, apparently signing gibberish.

He later said he is schizophrenic and had seen angels descending in the stadium where the event took place.

Settambrino said Florida, unlike some other states, does not require ASL interpreters to be certified through the Registry of Interpreters for the Deaf, a national nonprofit that 'seeks to uphold standards, ethics, and professionalism' for the field, according to its website.

Florida says only that ASL interpreters have to be 'qualified,' Settambrino said. 'But what is that definition of qualified?'