New Delhi | Delhi Police on Wednesday arrested one more accused, who was among the key conspirators in the GTB Hospital firing case, officials said.

According to the officials, the mastermind behind the incident, Faheem, had kept the accused Moin (19) as a backup plan in case the original plan failed.

"Moin visited GTB Hospital many times before the shooting incident and collected details about its entry and exit gates," Deputy Commissioner of Police (Shahdara) Surendra Choudhary said.

He conducted the recce for four continuous days along with associates Ayan, Aman and Shavez, who were inside the hospital at the time of the crime, he said.

"Initially, Moin was tasked to hide the motorcycle used in the crime. Beside that Faheem kept him as the backup plan in case of failure of the original plan," the DCP said, adding that further investigation into the matter is underway.

In a case of mistaken identity, 32-year-old Riyazuddin was shot dead by a teenager inside a ward of the GTB Hospital here on Sunday.

The police on Monday nabbed two accused -- Faiz (20) from Loni in Uttar Pradesh and Farhan from Delhi's Chauhan Banger area -- but said they did not fire the shots on Sunday evening, but provided logistic support to the main accused.

On Tuesday, the police said that a rival of jailed gangster Hashim Baba was the original target of the attackers.

The accused had gone to kill Waseem (33), who is facing multiple criminal cases and had threatened the jailed criminal over gang rivalry a few months ago, a police officer had said.

Faheem, who is a close associate of Hashim Baba, hatched the murder plan and trained the other accused on how they could enter the hospital and exit after the crime.

The accused are suspected to be the members of Hashim Baba's gang, the police said on Tuesday.