Pictured: Innocent baby cops say was killed by PhD student who also 'injured his twin' while sitting for close pal on wedding anniversary

The innocent baby cops say was killed by his Ph.D.-student babysitter has been pictured for the first time along with the twin brother she is also accused of injuring. 

Nicole Virzi is charged with the murder of six-and-a-half-week old Leon Katz at his home in Pittsburgh, on what was his dad's first Father's Day -- and his parents' first wedding anniversary.

Virzi, 29, was a 'trusted friend' of the babies' parents Ethan Katz and Savannah Roberts.

Police say she allegedly killed the infant while they were at the hospital with his twin brother Ari, who they allege Virzi also assaulted.

A GoFundMe set up for the devastated couple says Leon was 'tragically killed under horrific circumstances' and that a 'trusted family friend' has been arrested.

Virzi is charged with homicide, child endangerment, and aggravated assault but denies any wrongdoing.

Six week-old Leon Katz was murdered by a P.hD student babysitter hired by his parents, police say

Leon's alleged killer Nicole Virzi, 29, was a trusted friend of the infant's parents Ethan Katz and Savannah Roberts

Ethan and Savannah are pictured with Leon and his twin brother Ari, who Virzi is also accused of attacking 

Nicole Virzi is charged with the murder of six-and-a-half-week old Leon Katz at his home in Pittsburgh

'Leon will always be remembered as a happy, smiley, goofy baby boy. His untimely and tragic death has deeply impacted the Pittsburgh community, ' the GoFundMe reads.

Pictures taken just days before the tragedy show twins Leon and Ari side by side in matching onesies.

Virzi has denied any wrongdoing and her lawyer maintains her innocence. 

'Our client denies these allegations. She is a loving person and a friend to these people and would never harm anyone's child, let alone theirs,' her attorney David Shrager told Pittsburgh's WTAE.

The accused killer was continuing to babysit tiny Leon while his parents were at UPMC Children's Hospital of Pittsburgh with his twin, Ari, after Virzi said she spotted an injury on his groin area, police said.

This picture of the twin brothers was taken shortly before Leon's horrific murder and the attack on Ari 

The baby's killing came as their father celebrated father's day, which also fell on the boys' parents' first wedding anniversary 

She told cops that she had gone into the kitchen to get Katz a bottle when she suddenly heard screaming.

When she returned she said the baby had fallen out of his bouncer chair. She then called 911.

'The injuries sustained by both (twins are) consistent with having been sustained as a result of child abuse, as these are inflicted injuries that are not natural and not accidental,' a doctor told investigators, according to court filings.

Virzi is being held without bail at the Allegheny County Jail. She faces a preliminary hearing on June 28.

Her LinkedIn profile indicates she is a fifth-year clinical psychology candidate on the SDSU/UC San Diego Joint Doctoral Program.

Virzi, 29, seen in her booking photo, was babysitting the child while his parents were at UPMC Children's Hospital of Pittsburgh with his twin after Virzi said she spotted an injury on his groin

Virzi told cops that she was getting Katz a bottle when she heard screaming and saw he had fallen out of a bouncer

'She's going to be 30 years old. She's a Ph.D. student. She is long-term friends with the family in this situation,' Shrager said.

 'As I've said, it doesn't show any criminal history in her background and we're anxious to get our day in court.

'Right now, she's charged with a general count of homicide, which, for the most part, bond is not available. 

'Of course, we're going to be doing our due diligence on that end and see if we can make some changes there.'