Additional Sessions Judge PY Ladekar awarded capital punishment to Vishwajeet Masalkar, while terming the case as "rarest of the rare".
Mr Masalkar's mother Shobha (50), his wife Archana (25) and daughter were found murdered at their residence in Champaratna Apartment in upmarket Udaybaug area off BT Kawade Road on October 4, 2012. Mr Masalkar's 76-year-old neighbour, Madhusudan Kulkarni too was found seriously injured in the attack.
On the motive behind the crime, public prosecutor Ujjwala Pawar said Mr Masalkar, employed in a construction firm in Pune, was in a relationship with another woman in his office and was planning to get divorced from his wife.
He was working as a manager and his lover a supervisor at the same construction firm, located at Kharadi in the city.
Ujjwala Pawar said on the day of the incident, Mr Masalkar attacked his mother and wife with a hammer following heated arguments on the issue.
"The convict then returned home in the evening and cooked up a story and informed the police that unidentified people had killed his mother, wife, daughter and injured his neighbour before stealing gold ornaments and cash from his home," Ujjwala Pawar said.
Police, however, cracked the case with the help of CCTV footage of Mr Masalkar's residential society and on the basis of the statement given by the woman with whom he was having an affair with.
Police arrested him under sections 302 (murder), 307 (attempt to murder) and 201 (causing disappearance of evidence of offence, or giving false information to screen offender) of IPC.
The prosecution examined 16 witnesses during the trial. Depositions made by Mr Kulkarni and the woman proved crucial in the case.