Police in Buenos Aires have searched the house and private clinic of Leopoldo Luque as they try to establish if there was negligence in Maradona's treatment following surgery.
The 60-year-old died of a heart attack at his home where he was recuperating.
Dr Luque has not been charged. He denies any wrongdoing.
Maradona had a successful operation on a brain blood clot earlier in November and had been due to be treated for alcohol dependency.
His daughters have pressed for details about their father's medication.
What is the investigation centred on?
Some 30 police officers raided 39-year-old Dr Luque's house on Sunday morning - with another 20 going into his clinic in the capital Buenos Aires.
The raids were ordered by prosecutors trying to build a picture of Maradona's last days at home.
They retrieved computers, mobile phones and medical notes, officials say.
There are suspicions that the star's convalescence at home might not have met the conditions of his discharge from the clinic, such as a 24-hour team of nurses "specialised in substance abuse", the on-call presence of doctors and a stand-by ambulance equipped with a defibrillator.
Officials want to know about Dr Luque's involvement in Maradona's recovery arrangements at the late star's house.