Peter Wertheimer was born in Satu Mare, in the far north-west of Romania, on 21 July 1947, and grew up in Timișoara. His father, Andrei Wertheimer, was a violinist and an opera concertmaster who had been one of the first people to play jazz in that city. Peter started on classical violin at five, under his father, and went on to the music school in Timișoara and then to the National University of Music in Bucharest.

The conservatory expelled him. He had been caught playing jazz, which was not permitted there, and the expulsion came with a ban on returning. It is the fact that shaped everything after it, and it is the reason a musician of his level spent his twenties working outside the institutions rather than inside them: nightclubs, cafés, culture houses, the Sándor Petőfi club in Bucharest.

He found his way into the state music apparatus anyway. He joined the Electrecord light-music orchestra, the house band of Romania's state record label, and toured with it to Warsaw in 1974, to Hamburg, where he worked with the American drummer Billy Brooks, and to Switzerland. More importantly, he fell in with the small circle that was Romanian jazz in the 1970s: the bassist and pianist Johnny Răducanu, whom Leonard Feather nicknamed Mr. Jazz of Romania, the drummer Eugen Gondi, and the pianist and composer Marius Popp. Romanian critics of the period wrote about Wertheimer as a Charlie Parker devotee with a complete technique. His two lasting recordings from those years are Răducanu's Jazz În Țara Mea (Electrecord, 1976) and Popp's Panoramic Jazz Rock (Electrecord, 1977), the second of which has him on alto, baritone and soprano saxophone across a jazz-rock session that has been reissued repeatedly since.

In 1977, at thirty, he emigrated to Israel. He settled first on a kibbutz near Rehovot and then in Tel Aviv, and with help from the producer Nancy Brandes he was working inside the Israeli record industry within months, starting with a session behind the singer Ilanit.

What followed was one of the most-recorded careers in Israeli music and one of the least visible. Ninety documented releases carry his name from 1978 onward, eighty-one of them dated between 1978 and 2014, and not one is billed to him. He is on Arik Einstein records, on Matti Caspi's, on Chava Alberstein's Voices (1982), on Yehudit Ravitz, Gidi Gov, Gali Atari, Yardena Arazi, Danny Sanderson, Shem-Tov Levi, Boaz Sharabi and Nurit Galron. He is also on Rami Fortis's Plonter (1978), widely called the first Israeli punk record, on the cantor Dudu Fisher's Yidishkiet, on the Hasidic singer Avraham Fried's Aderaba, on the kibbutz choir the Gevatron's The Beloved Valley, and on children's records and Festigal compilations. Hebrew coverage of his career puts the total in the hundreds of sessions, spread across jazz, light music, classical, Hasidic and klezmer repertoire, film and stage scores.

The clearest single demonstration of what he could do is Rafi Kadishzon's score for Renen Schorr's Late Summer Blues (1987). Wertheimer is credited on it three times on three different instruments: the main theme on alto saxophone, "Dawn at the Seashore" on clarinet, and the main theme again on flute. In 1996 Kadishzon wrote him a piece of his own, a Concerto for Peter and Orchestra.

Alongside the session work he kept a jazz life going. He played as a soloist with the Israel Philharmonic Orchestra, worked in jazz arrangements of Bach, and performed with the core of the older Israeli jazz generation: the pianist Dan Gottfried, the drummer Arale Kaminsky, the saxophonist Albert Piamenta, the bassist Eli Magen, and the singer Edna Goren. He also appeared as an actor in Israeli films, including Ze'ev Revach's Talveh Li Et Ishtecha (1988) and Sochrei HaGumi (2001), and on the long-running children's television programme Parpar Nechmad.

The one record billed to him arrived from Romania, not Israel, and eighteen years after he had left. Flașnetarium (Electrecord EDE 04401, 1995) is credited "Marius Popp invitat Peter Wertheimer": six Popp compositions, Wertheimer on soprano and alto saxophone, Tudi Zaharescu on drums and Cătălin Rotaru on bass, closing on a piece called "Duke Remember".

His widest international exposure also came from the Romanian years and arrived thirty years late. In 2007 the Berlin production team Jazzanova compiled Romanian Jazz: Jazz From The Electrecord Archives 1966-1978 for the label Sonar Kollektiv, and Wertheimer's saxophone and flute on Marius Popp's "Xybaba", at 11:27 the longest track on the record, went out to a global audience that had never heard of him.

Recognition in Israel came late and mostly in the form of tributes. The Israel Chamber Orchestra Jerusalem gave a concert for his sixtieth birthday in 2007. The Jerusalem Post covered a Tel Aviv concert in his honour in June 2015 under the headline "Playing with love". He married the actress Adi Lev in 1981; she passed away in 2006, and they had two children, Alon and Shirley. Peter Wertheimer passed away in Tel Aviv on 5 January 2020, at 72, after a long illness with cancer, and was buried in the old cemetery in Herzliya. In a hospital interview given weeks earlier he said he remained optimistic and hoped to feel well again soon.

Wertheimer came out of bebop. The Romanian writing on him from the 1970s names Charlie Parker as the model and credits him with a complete technique, and the alto playing on Panoramic Jazz Rock carries that lineage into a jazz-rock setting: fast, articulate, harmonically direct lines over Marius Popp's electric piano. The Romanian jazz of that circle, Răducanu and Popp in particular, worked at folding Romanian folk material into a jazz frame, and Wertheimer was the horn that had to make those hybrid forms swing.

His classical foundation was real rather than nominal. He began on violin at five, trained through the Bucharest conservatory system, and later played as a soloist with the Israel Philharmonic Orchestra and made jazz arrangements of Bach. That training is what made the second half of his career possible: the reason producers called him for four decades is that he could bring a jazz musician's phrasing to any idiom placed in front of him and read whatever was on the stand.

The defining trait is range of instrument rather than range of style. Across the catalogue he is credited on soprano, alto, tenor and baritone saxophone, on clarinet, on flute and on violin, and he moved between them within single projects. The Late Summer Blues score has him carrying the same melody on alto saxophone and then on flute, and the Flașnetarium sleeve splits his tracks between soprano and alto. He worked the same way across genre: jazz, Israeli pop and rock, Mizrahi, Hasidic, klezmer, children's music and film, often in the same years, which in Israeli music of the 1980s meant crossing between audiences that did not otherwise overlap.