PHILADELPHIA — A Philadelphia lawyer stands accused of trying to file an unauthorized civil lawsuit on behalf of the father of a 12-year-old boy who was fatally shot by police and also asking a judge to declare the man mentally incompetent in a bid to keep the case and cash in on a potential settlement.

The misconduct allegations against J. Conor Corcoran, a civil litigation lawyer, were detailed in a petition filed by the state’s Office of Disciplinary Counsel in December, according to The Philadelphia Inquirer. The matter was first reported by Axios.

Corcoran’s attorney, Samuel Stretton, told The Inquirer that Corcoran had “good intentions” in the case. Stretton said the matter is the result of multiple lawyers competing for a stake in a high-profile case.

According to the filing, Thomas Siderio Sr. hired Corcoran to represent him in a separate, unrelated police brutality cases but did not hire Corcoran to represent him after his son, Thomas “T.J.” Siderio, was fatally shot by Officer Edsaul Mendoza in March 2022.

Two days after the child was killed, Corcoran filed a writ of summons attempting to have Siderio named as administrator of his son’s estate, according to the petition — without having even met with or spoken to Siderio about the matter.

The next day, Corcoran went to the state prison where Siderio was serving a sentence for a weapons charge and tried to meet with him, the complaint states. But he was denied entry because he was not listed on Siderio's attorney visitation list.

Stretton said Siderio reached out to Corcoran in subsequent days and that they discussed the case four times between March and May 2022. Corcoran also spoke with Siderio’s mother, Desirae Frame, and other relatives, Stretton said.

Even though Corcoran and the boy's father never signed a new fee agreement, Stretton said Corcoran believed he continued to serve as Siderio’s attorney in civil matters.

Siderio and Frame eventually hired different attorneys to represent them in the case, but Corcoran continued to claim he represented Siderio, according to the filing. He also allegedly sent emails to the family’s retained lawyers threatening to file complaints against them.

In June, Corcoran filed a court petition asking a judge to find Siderio incapacitated and appoint a guardian to oversee his estate and civil cases, according to the filing. The disciplinary board said Corcoran lied about Siderio’s mental troubles and did not attach any expert medical reports to support the claims.

He also requested that Siderio and Frame's attorneys be removed from the case. Stretton said Corcoran “was trying to protect Mr. Siderio” from the other lawyers.

A judge dismissed both requests and Corcoran withdrew his civil action in July 2022, saying the family was being represented by other attorneys.

The disciplinary counsel's filing claims Corcoran's actions were a money grab and part of “an attempt to force his representation on Siderio and secure substantial attorney’s fees."

In a response filing, Stretton said Corcoran is regretful about how the matter played out and acknowledges he was wrong in believing his first fee agreement with Siderio covered the case.

The Pennsylvania Supreme Court's Disciplinary Board has scheduled a June hearing to consider the complaint.