New York prison break: Fugitive Richard Matt gave prison worker Joyce Mitchell a painting of her children before he escaped

A District Attorney said that Mitchell was previously investigated for having an inappropriate relationship with Matt

Joyce Mitchell, left, is accused of aiding the escape of two convicted murderers from a high-security prison in New York (G.N. Miller - Pool/Getty Images)

A convicted murderer on the run from a high-security prison made a painting of the children of the prison staff member accused of helping him escape, a New York District Attorney has said.

Speaking to CNN, District Attorney Andrew Wylie said that at one point before the escape, escaped prisoner Richard Matt made a painting of prison tailor shop worker Joyce Mitchell's children, which he gave to her as a present.

Wylie said that Mitchell gave Matt's painting to her husband as a wedding anniversary present.

As reported by CNY Central, Matt is a talented artist, and kept in touch with former prisonmates by sending them some of his paintings of notable figures such as Angelina Jolie and Oprah Winfrey.

Police have released images of what David Sweat, left, and Richard Matt could look like after almost two weeks on the run. (New York State Police/Getty)

Joyce Mitchell, 51, was a tailor shop instructor at Clinton Correctional Facility in Dannemora, New York. Matt is a convicted murder, serving 25 years to life for his 1997 kidnap, torture and dismemberment of 76-year-old William Rickerson.

Together with fellow convict David Sweat, he escaped the high-security prison on 5 June. A large-scale manhunt is underway to find the criminals, and Joyce Mitchell is accused of helping the men escape, by providing them with hacksaw blades, chisels, and other tools.

She has pleaded not guilty to two charges, one felony charge of promoting prison contraband, and a misdemeanour charge of criminal facilitation. She could face up to eight years in prison if she is found guilty.

Mitchell has been investigated in the past for having an inappropriate relationship with Matt. Wylie said that corrections officials moved Matt out of the tailor shop in 2013 to keep the two separated.

US Marshalls and police officers go door-to-door searching for the escaped criminals. (Andrew Burton/Getty Images)

Mitchell's husband, Lyle, also worked in the prison's tailor shop. Wylie said that he had no idea about the prisoner's escape plan, and was not aware of his wife's relationship with the inmates.

The search for the escaped pair has entered its 14th day, and has involved 600 law enforcement officers from local, state, and federal levels. The officers have combed around 16 square miles of land near the prison in their search.

New York State Police Major Charles Guess has told a press conference that police have developed more than 1,400 leads.