What is the test for establishing a conspiracy?

"In proving a conspiracy, . . . it is not necessary to demonstrate that the parties met and actually agreed to undertake the unlawful act or that they had previously arranged a detailed plan. The evidence is sufficient if it supports an inference that the parties positively or tacitly came to a mutual understanding to commit a crime. Therefore, conspiracy may be proved through circumstantial evidence inferred from the conduct, relationship, interests, and activities of the alleged conspirators before and during the alleged conspiracy." (People v. Prevost (1998) 60 Cal.App.4th 1382, 1399; see People v. Vu, supra, 143 Cal.App.4th at pp. 1024-1025 ["The elements of conspiracy may be proven with circumstantial evidence, 'particularly when those circumstances are the defendant's carrying out the agreed-upon crime.'"].)

C. Analysis

1. Forfeiture