What was Theo Theodorakis' motive to murder Sam Westing in The Westing Game?

Sam Westing is not actually murdered by anybody, but the guests of the Sunset Towers are not privy to that information. They all believe that he is dead, and they believe that one of them is guilty. The 15th clue really drives home the idea that Westing is dead and one of the tenants is guilty.

And time is running out. Hurry, find the name before the one who took my life takes another.

Theo's motive is essentially the same as everybody else's motive. The Westing fortune is large, and having that money would be a huge blessing in Theo's life. The idea of Theo committing murder to gain a lot of money for himself is completely absurd. When Theo was asked his "position," he wrote down "brother." He sees himself as second. Chris is more important, and Theo sees himself as the brother. Chris is not Theo's brother. Theo is Chris's brother. If I had to come up with a reason for Theo to kill Westing, it would be to obtain money that would be used to care for his brother and family. That's not unrealistic. Readers find out in chapter 8 that Theo plans to give half of his $10,000 to his parents and half to his friend.

First, the money. They signed their names to the check; half would go into Doug Hoo’s savings account; half would go to Theo’s parents.

Who in "The Westing Game" would have a motive for killing Sam Westing, if he were murdered?

Any and/or all of the characters that got a letter to partake in the "game" have motives to kill Sam Westing; this is one reason why they all suspect each other. They all know that each person has his or her own reasons for killing Mr. Westing; however, they all share one similar reason. Mr. Westing is very wealthy, and they each stand to gain a lot by having access to that money.

For example, Chris Theodorakis has motive to do it and an alibi. Nobody would suspect him of killing Mr. Westing because of his wheelchair and condition, but Mr. Westing's money would allow him to seek the treatment he needs for his unknown illness. Angela Wexler has motive too. The money would grant her independence from her mother. Angela had a taste of that kind of independence from when she went to her one year of college, and she would like to be a doctor someday; however, she doesn't have the money to do that. Westing's fortune could make that happen.

In Ellen Raskin's novel The Westing Game, Sam Westing is a millionaire who dies. In his will, he claims he was murdered, that one of his heirs (sixteen nieces and nephews) did it, and that if they participate in a game, they will be given clues that will reveal the identity of the murderer. 

Many of the heirs had motives to kill Sam Westing. James Hoo is a restaurant owner who is bitter and believes Sam Westing stole an idea from him that made Sam prosperous and left James Hoo struggling. In a phone conversation, one of the heirs, J.J. Ford, finds out about the motive of James Hoo. 

Mr. Hoo waddled in with a tray of appetizers. The judge pointed him to the serving buffet and apologized to her caller. "I'm sorry, would you repeat that name?"

"James Hoo. He claimed Westing stole his idea of the disposable paper diaper." 

Berthe Erica Crow was married to Sam Westing, and when the heirs get all the clues together, the missing letters from the stanza of "America the Beautiful" spell out her name. Since they were married previously, she could have motives for killing him due to the nature of their failed relationship, and a desire to get her share of his wealth. 

At one point, Sydelle Pulaski hints that the murderer may be Chris Theodorakis because, as she says: "A wheelchair, what a perfect alibi." However, no motive is given for him to be the murderer.

Grace Wexler is an unlikeable character in many ways. She is pretentious and desires the inheritance money. She makes racist comments toward the judge and treats her daughters unfairly. But just being unlikeable doesn't prove a motive for murder. 

Of course, in the end, readers learn there was no murder committed.  

What was Angela Wexler's motive for killing Sam Westing in "The Westing Game"?

Angela Wexler's possible motive for killing Sam Westing might be to gain his inheritance.  The money would allow her be independent, and pursue the career that she longs to have.

Intelligent and beautiful, Angela Wexler exists completely under her mother Grace's control.  Grace has arranged for Angela to marry Dr. Denton Deere, and is revelling in the excitement of wedding preparations and plans for Angela's life.  "Perfect Angela" (Ch.14), though, does not want to get married yet, but is too timid to stand up to her mother;  whenever Grace wants something, "Angela does everything she says" (Ch.12)  Angela chafes about being asked about Denton "all the time, as though she was nobody" (Ch.14).  Although she is admired for her beauty, Angela is never asked about her own hopes and dreams.  No one cares to know who she really is, and she is starved for attention.

Angela had gone to college for a year, and often wonders about the exciting lives her friends must be living now, with their careers.  She herself wants to be a doctor, but does not have the money nor the will to make her dreams come true.  It is possible that Angela thinks that her potential inheritance from Sam Westing might help her eliminate at least one of the impediments to achieving her aspirations.

Who has a motive to kill Sam Westing in "The Westing Game"?

Many of Sam Westing's heirs had motives to kill Mr. Westing. Grace Wexler is an ostentatious woman whose desire for wealth would be a major motivation for murder. Bertha Crow, who was married to Mr. Westing at one point, would have a motive for murder if she harbored resentment over their failed relationship. If she felt she had been callously discarded by Westing, she would feel bitter and angry. Her anger over their past could have driven her to murder, especially if she also believed she would get a bit of his riches after his demise. Another character who had a motive to kill Sam Westing would be James Hoo. James believes Mr. Westing stole an idea from him. The idea, which was to make a disposable diaper, made large sums of money for Westing. Without his grand idea, Mr. Hoo is left to struggle financially. Hoo's anger toward Mr. Westing would give him plenty of motivation to murder him.

What is Chris Theodorakis' motive in Sam Westing's murder in "The Westing Game"?

Theoretically, Chris Theodorakis's possible motive in the the Sam Westing murder is to get the money he needs for treatment for his unidentified illness.  Chris had been "a perfectly normal kid" until about four years ago.  He started "to get clumsy, just little things at first", but the illness progressed until now, he is confined to a wheelchair, unable to control the severe spasms which wrack his body.  Chris, who has a special interest in ornithology, is intelligent and good-natured, completely in touch with what is going on around him, which makes his physical handicap that much more difficult to accept.  There is apparently an experimental operation available that might help him, but it is very expensive.

Despite the fact that he does have a motive to want Sam Westing's inheritance, it is highly unlikely that Chris is the murderer.  Chris does not dwell on his physical limitations, and in more than a few instances, it is pointed out that his interest in the Westing Game is based on his delight in being "part of the outside world".  He guards his clues and insights into the case carefully, doling them out sparingly to his partner, Denton Deere, so that the doctor will have to interact with him as long as possible.  Chris had never "asked for charity...all he wanted was to play the game".

Why would Angela want to kill Sam Westing in The Westing Game?

Let me start by saying that Angela Wexler did not kill Sam Westing. Sam Westing faked his own death and is not dead during the events of the story. Angela Wexler could have motivations to kill Sam Westing; however, her motive for killing Sam Westing would be almost exactly the same motive as most everybody else's motive for killing Sam Westing.

Angela would kill Westing in order to secure for herself all or some of the inheritance money. In my opinion, this is a stretch, because she is not a close relative of Westing. Angela Wexler is Westing's grand-niece. Grace Wexler is Angela's mother, and she claims that Sam Westing is her uncle. This is likely true, since Angela looks a lot like Westing's daughter, Violet. This is something that Flora points out to the judge in chapter 13.

“Angela will make such a beautiful bride. Funny how she reminds me of her.”

“Angela reminds you of your daughter?” the judge asked.

“Oh my, no. Angela reminds me of another young girl I made a wedding dress for: Violet Westing.”

Westing's fortune would be something that Angela would want and be able to use. She yearns to follow her own dreams and passions, but she feels overly controlled by her mother. Angela is being married off to someone that she doesn't really want to marry, and the only thing people ever notice about her is her looks. Angela is so troubled by all of this that she intentionally mars her looks in order to gain freedom, and Westing's money would give her the financial freedom to pursue her own dreams.