Waldman graduated from the Cooper Union for the Advancement of Science and Art in June 1916 with a degree in engineering. However, he really wanted to be a lawyer and while working as a construction engineer during the day attended law school in the evenings. During the First World War the Socialist Party of America (SPA) took an anti-war stance. In 1917 Waldman was elected to the State Assembly.

In 1919 Waldman was elected along with four other Socialist Party comrades, August Claessens, Samuel Orr, Charles Solomon, and Samuel A. DeWitt. However, as the New York Times pointed out: "Waldman, running in Manhattan on a Socialist ticket, won a seat in the Assembly three times. But in 1920, the Republican-dominated Legislature expelled him and three colleagues for their membership in the Socialist Party, an action that widely criticized at the time."

Waldman was admitted to the New York State Bar in 1923 and became counsel for the Amalgamated Clothing Workers of America. He also worked for other unions in the city. In 1924, he ran as the representative of the Socialist Party of America for New York Attorney General. Waldman was elected chairman of the party in New York state in 1928, a position which he retained through the first half of the 1930s. He also stood as the SPA candidate for Governor of New York in 1928, 1930 and 1932.

During this period Waldman was seen as the leader of the "Old Guard" faction, which supported working closely with the union movement. This brought him into conflict with the "Militant" faction that favoured a closer relationship with the American Communist Party. Eventually, the leader of the SPA, Norman Thomas, gave his support to the the group opposed to Waldman. Bertram D. Wolfe pointed out: "For some time there has been growing discontent manifested within the ranks of New York Socialists, especially among the younger elements, against the methods used by the Jewish Daily Forward crowd in fighting the Communists, in opposing the united front proposals of the American Communist Party, in splitting unions and other labor organizations and expelling progressive and left wing elements, in using gangsterism — in short, in all the methods employed by the old socialist leadership to ruin the labor movement that they can no longer rule. Even a small section of the leadership, such men as Norman Thomas, have been criticizing these policies...because they are causing a further loss of membership and a further disintegration of the Socialist Party."

Waldman wanted the Socialist Party of America to support Franklin D. Roosevelt in the 1936 Presidential Election. When this policy was rejected he joined with Abraham Cahan, Sidney Hillman, Vito Marcantonio and David Dubinsky to establish the American Labor Party (ALP). The ALP put forward a left-wing, non-socialist, program. Its 1937 Declaration of Principles stipulated that there should be a "sufficient planned utilization of the natural economy so that coal, oil, timber, water, and other natural resources that belong to the American people... shall be protected from predatory interests."

In April 1939, Walter Krivitsky, a former NKVD agent, published an article in the Saturday Evening Post. Krivitsky received little support from the administration of President Franklin D. Roosevelt. One of his advisors, Adolf Berle, commented, that as far as he was concerned Krivitsky was "a former chief of spy service who is turning state's evidence now that he has been thrown out". Waldman used the material in his speeches against the dangerous influence of communists in America but said he "felt disinclined to place a halo on the head of a person simply because he had broken with the Communist dictatorship after years of blind and faithful service."

Krivitsky was in danger of being deported. Isaac Don Levine introduced Krivitsky to Waldman. Gary Kern, the author of A Death in Washington: Walter G. Krivitsky and the Stalin Terror (2004), has argued: "Louis Waldman was a socialist, labor reformer and campaigner for honest government... Phenomentally active, he divided his time between private practice, speaking engagements and membership on numerous boards, bars and associations." Waldman agreed to become Krivitsky's lawyer. He told his new client that as deportation would mean physical danger to himself and his family, then "a presentation of these facts to our immigration authorities would prevent such action." In other words, the government would not send him back to the Soviet Union if he was likely to be killed.

On Sunday 9th February, Walter Krivitsky checked into the Bellevue Hotel in Washington at 5:49 p.m. He paid $2.50 in advance for the room and signed his name in the register as Walter Poref. The desk clerk, Joseph Donnelly, described him afterwards as nervous and trembling. At 6:30, he called down for a bottle of Vichy sparkling water. The bellboy considered him a typical foreigner - "quiet and solemn".

The young maid, Thelma Jackson, knocked on Krivitsky's room at 9.30. When she did not receive an answer she assumed the room was free for cleaning and inserted her passkey. She opened the door and discovered a man lying on the bed the wrong way round, with his head toward the foot. She noticed he had "blood all over his head". The police were called and Sergeant Dewey Guest diagnosed the case as an obvious suicide. Coroner MacDonald issued a certificate of suicide that afternoon.

Krivitsky left behind three suicide notes, each one in a different language known to him (English, German and Russian). Police handwriting expert, Ira Gullickson, was shown the notes found with the body and declared that they were without any question written by the man who signed the hotel register. Gullickson argued that the notes were written on different times, because they showed an increase in nervous tension.

The first letter, in English, was addressed to Louis Waldman: "Dear Mr. Waldman: My wife and my boy will need your help. Please do for them what you can. I went to Virginia because that there I can get a gun. If my friends should have trouble please Mr. Waldman help them, they are good people and they didn't know why I bought the gun. Many thanks."

The second suicide note, in German, was addressed to Suzanne La Follette: "Dear Suzanne: I believe you that you are good, and I am dying with the hope that you will help Tonia and my poor boy. You were a good friend." This letter raised several issues. It is true that in the early days of their relationship he did write in German because his English was poor. However, in recent letters, he had used English.

The third letter was to his wife, Antonina Porfirieva: "Dear Tonia and dear Alek. Very difficult and very much want to live but I can't live any longer. I love you my only ones. It's difficult for me to write but think about me and you will understand that I have to go. Don't tell Alek yet where his father has gone. I believe that in time you will explain since it will be good for him. Forgive difficult to write. Take care of him and be a good mother - as always be strong and never get angry at him. He is after all such a such a good and such a poor boy. Good people will help you but not enemies of the Soviet people. Great are my sins I think. I see you Tonia and Alek and embrace you."

Gary Kern, the author of A Death in Washington: Walter G. Krivitsky and the Stalin Terror (2004) claims that two sentences in this letter cause certain problems: "Good people will help you but not enemies of the Soviet people. Great are my sins I think." He goes on to argue: "These two statements have the look of a political recantation and, as such, suggest either a mental breakdown or something dictated by the NKVD."

On hearing of Krivitsky's death, his lawyer, Louis Waldman, called a press conference and announced that he had been murdered by the NKVD and named the killer as Hans Brusse. (1) An NKVD agent (Hans Brusse) who had twice before tried to trap Krivitsky had appeared in New York City, where Krivitsky lived. (2) Krivitsky planned to buy a farm in Virginia, thus he intended to live. He had changed his name, applied for citizenship, bought a car. (3) The NKVD was expert in forgery and had samples of Krivitsky's hand in every language.

At the White House, Adolf Berle, President Roosevelt's advisor on national security wrote in his diary: "General Krivitsky was murdered in Washington today. This is an OGPU job. It means that the murder squad which operated so handily in Paris and in Berlin is now operating in New York and Washington." Joseph Brown Matthews, who was an investigator for the House Committee on Un-American Activities, commented: "It's murder. I have no doubt of it." New York Times reported that Krivitsky had told them: "If they ever try to prove that I took my own life, don't believe them."

One of the most surprising aspects of the case was that rooms on both sides of Krivitsky had been occupied. So had the rooms across the hall. In the past, guests had often complained about noises in the room next to them because of the thinness of the walls. However, no one heard gunfire in the quiet early morning hours when the suicide had taken place. The gun found in Krivitsky's room did not have a silencer.

The Washington Post argued: "All in all, it would seem that the Washington police and coroner disposed of the case in rather summary fashion... The whole thing looks like a pretty careless piece of work." Frank Waldrop of The Washington Times-Herald ridiculed the police investigation: "Anybody'd rather be a second-guessing citizen than Chief of Police Ernest W. Brown, with such a staff of lunkheads to do the field work in homicide matters." However The Daily Worker disagreed: "The capitalist press is desperately trying to make a frame-up murder case out of what is clearly established in the suicide of General Walter Krivitsky."

Alexander Kerensky believed Hans Brusse had murdered Krivitsky: "Hans Brusse is the man. The most vicious murderer in all the Soviet. We know him. We know his methods. His favourite tactic is to drive a man to suicide by threatening to capture and torture his family. It has been done many times in many countries. I believe Krivitsky got a concrete warning recently that they would kill him or kidnap his family. That is their favourite plan of operation. Krivitsky had a burning mission to expose Stalin for what he is. And in my opinion he was not the type to commit suicide."

Whittaker Chambers definitely believed that he had been killed by the NKVD: "He had left a letter in which he gave his wife and children the unlikely advice that the Soviet Government and people were their best friends. Previously he had warned them that, if he were found dead, never under any circumstances to believe that he had committed suicide." Krivitsky once told Chambers: "Any fool can commit a murder, but it takes an artist to commit a good natural death." Martin Dies, Isaac Don Levine and Suzanne La Follette all believed Krivitsky was murdered.

However, Eitel Wolf Dobert, told reporters that Krivitsky seemed very worried and probably had committed suicide. He also thought that Krivitsky had written his suicide notes the last night that he stayed on his farm. Mark Zborowski, who was later exposed as a NKVD agent who had been involved in the death of Lev Sedov, also believed Krivitsky committed suicide. He told David Dallin: "He was a neurasthenic and a paranoiac, eternally in fear of assassination. He felt that he was a traitor. As a Communist, he did not have the right to do what he was doig. He had days of high spirits and days of dejection."

Paul Wohl also disagreed he had been murdered. He said: "When we lived together, he often talked of suicide." Wohl also dismissed the idea that Hans Brusse killed Krivitsky. He claimed that although he was a Soviet agent he was not the type "to be assigned to assassinations, but rather a technician". Gary Kern, the author of A Death in Washington: Walter G. Krivitsky and the Stalin Terror (2004) has pointed out: "If Hans were so innocuous, one has to wonder, then why had Wohl sent his letter of warning to Krivitsky in the first place... And if he were not an assassin, but a technician, then what was he doing in America on a political assignment? And how did Wohl, a private citizen, know about any of these things?"

Jan Valtin, a former NKVD agent also took the view that Krivitsky was murdered. He said the NKVD liquidated people on foreign soil for three main reasons: "(1) To silence someone with secrets who might talk, has talked or will go on talking. (2) To eliminate someone who could be an asset to foreign intelligence services. (3) To wreak vengeance on someone who tried to break away from the Soviet Secret Service and thus to demonstrate an ability to prosecute defectors anywhere in the world, with the consequent chilling effect on potential defectors still in the service."

Another former agent, Hede Gumperz, also explained how they would have arranged his death. "The only possible lever they could have tried to use against him was his family - threatening to kill his wife and son, and promising to spare their lives only if he took his. But Krivitsky would have known with absolute certainty that, even if the threats were serious, the promises were not. After all, he himself, as a senior officer in the same service, had seen so many promises of clemency which had been made in the name of Stalin cynically broken the moment their aim was achieved."

Krivitsky's wife, Antonina Porfirieva, believed it was a forced suicide. The main clue came from his letter: "Very difficult and very much want to live but I can't live any longer. I love you my only ones. It's difficult for me to write but think about me and you will understand that I have to go." Antonina, who had worked for the NKVD and knew about the methods they used: "I am convinced that my husband was forced to write the notes he left behind... Walter had utter contempt for suicide and would have never killed himself willingly. They forced him to write those notes and then they forced him to kill himself. He made a deal with them to save me and our boy."

Louis Waldman campaigned for the FBI to treat the case as murder. "The issue is much deeper than the discovery of whether the general's death was the result of murder or suicide... When one considers that General Krivitsky was a witness, giving valuable information as to foreign espionage in our own country to a legislative committee, to the State Department, and to the FBI itself, then in my opinion, there is the clear duty of the FBI to track down those malevolent forces which were responsible for his death."

Waldman told the FBI that he had evidence that Hans Brusse was the killer. When the FBI reopen the case he went to the press with his evidence. Recently released documents show that in March 1941 a certain Lee Y. Chertok, a Russian living in the United States, claimed to have information on the killers of Krivitsky. J. Edgar Hoover sent a memo telling the FBI not to follow up this evidence: "The Bureau is not interested in determining whether Krivitsky was murdered or whether he committed suicide."

Waldman was a supporter of Martin Luther King and the Civil Rights Movement. However, he questioned some of the methods he used: "Those who assert rights under the Constitution and the laws made thereunder must abide by that Constitution and the law, if that Constitution is to survive. They cannot pick and choose; they cannot say they will abide by those laws which they think are just and refuse to abide by those laws which they think are unjust.... The country, therefore, cannot accept Dr. King’s doctrine that he and his followers will pick and choose, knowing that it is illegal to do so. I say, such a doctrine is not only illegal and for that reason alone should be abandoned, but that it is also immoral, destructive of the principles of democratic government, and a danger to the very civil rights Dr. King seeks to promote."

Louis Waldman died on 12th September, 1982.