In 1890 graduated from the law faculty of St. Petersburg University. Was appointed to the work district judicial investigator, where he worked for fifteen years with a break.
From 1897 he served in the Petersburg District Court - in the first instance as an investigator.
1909 investigator for particularly important cases.
Since 1916 was an investigator for particularly important cases in St. Petersburg court. Investigating cases of attempted murder of Prime Minister Sergei Witte, case about the poisoning Mr. Buturlin from Dr. Panchenko, case the murder of actress Ms. Timme, case Mr. Orlov-Davydov and artist Mr. Poiret, case about swindler Ms. Olga Stein, case about teacher-lecher Mr. Du-Lu, the case of the death of the son of Admiral Mr. Crochae, case of a fire at St. Petersburg folk house from the fault Prince of Oldenburg and others. He earned a reputation as an impartial, and faithful truth criminalist, had political impartiality, ensuring public confidence in the results of his investigation.
At the beginning of 1917 Aleksandrov was a teacher of "production techniques of investigation for espionage affairs" at the school of counterintelligence at the Main Directorate of the General Staff of the Russian Empire. As to the judicial investigation of treason citizen of the Russian Empire of Vladimir Lenin and the Bolsheviks - Mr. Alexandrov sewed to Volume 11 of the case filed testimony from chief central department of counterintelligence at the Main Directorate of the General Staff of Mr. Medvedev, and Volume 13 of the case - fully compiled of agential of the material of counterintelligence.
After the February Revolution, Justice Minister Mr. Skaryatin made seconded Mr. Alexandrov to special commission of inquiry, which investigated the activities of the "Union of the Russian People", case «Manasevich-Manuylov», case «Bielecki», case «Protopopov» and others. In July 1917, Mr. Alexandrov submitted to a commission of inquiry to investigate «July events» 3–5 July. Counterintelligence gave for examining magistrate Mr. Alexandrov several cupboards, that compromising citizens of the Russian Empire the Bolsheviks and Vladimir Lenin. For Mr. Alexandrov was requested to present a formal public prosecution against Vladimir Lenin on the basis of "a criminal act under 51, 100 and 108 § 1 of Art. Criminal LawCode of the Russian empire".
In mid-April 1917, Alexandrov opened a criminal case against Lenin and the Bolsheviks. On October 17, 1917, Alexandrov interrogated the last witness - Mr. Alexeev. The case against the Bolsheviks was never completed, because the person under investigation, Vladimir Lenin, organized a coup d'etat in October 1917, when was scheduled court hearing of his crime. The criminal case was so important that the confiscation of his 21 volumes was the first command of the new government, the future USSR, and the second stage - the attack oh the Winter Palace.
October 21, 1918, Alexandrov was arrested by the Cheka in USSR, because of his conscientious performance of official duties in the public service in the Russian Empire. Arrested at the station Veimarn Baltic Railway. Together with his son-in-law concluded in concentration camp with the phrase - "before the end of the Civil War" ; his daughter released. A July 26, 1919, at the request Demyan Bedny addressed to Felix Dzerzhinsky released son-in-law.
In 1925, again he gave explanations in Soviet law enforcement agencies after arrest. At the time, he worked as head of the department of incidents on "October railway" in Moscow.
April 5, 1928 again he arrested and imprisoned. Sentenced to 5 years "Labor camp" and sent to a concentration camp USSR.
In early 1929 his wife requested application in "Political Red Cross" for facilitating repression. In the case of Mr. Aleksandrov preserved note from Anatoly Lunacharsky :
In 1932 - he was released early from the concentration camp USSR and sent to get off the remaining term in Siberia.
In the mid-1930s - after his release he returned to Moscow and worked as a legal adviser in the office of the Chief Supply Management sugar industry Commissariat food industry.
17–18 November 1939, was arrested at night without the production of a criminal case, in violation of regulations Presidium Central Executive Committee of the USSR on November 2, 1927: "On amnesty to mark the 10th anniversary of the October Revolution". Because there was a request of the security organs «KGB» not to apply amnesty to Mr. Aleksandrov. This had adopted Prosecutor's Office the USSR May 22, 1939. This was decided on this at the Presidium of the Supreme Soviet of the USSR 11 November 1939. At the time of his arrest, he worked as a legal adviser in the economic office supplies. Mr. Alexandrov survived with dignity on interrogations.
September 24, 1940 was shot. Buried in «Donskoi Cemetery». The entire history of the Soviet Union became the confirmation of the validity of acts lawyer Mr. P. A. Aleksandrov.
Career colleagues Mr. P. A. Alexandrov lawyer Andrey Vyshinsky turned out differently, though A. Vyshinsky signed order for the arrest of a state criminal V. I. Ulyanov. Since Andrey Vyshinsky contrary "professional ethics" became a member of a political party to the RSDLP before 1917, and his immediate supervisor in violation of the "secrecy of the investigation", warned the head of the RSDLP V. I. Ulyanov about arrest, to facilitate his escape and concealment from justice. It was in this atmosphere made investigation nonpartisan Mr. Alexandrov with tragic consequence of these circumstances for the investigation and history of the people.
His wife Katherine Ivanovna Alexandrova, had secondary education, housewife. In 1929 - after sending her husband in a concentration camp USSR, she lived with relatives in Pyatigorsk. In the autumn of 1933 - arrested in Pyatigorsk. December 12, 1933 was sentenced to three years' exile in Siberia and sent to the Tomsk Oblast.
